Method of Operating A Robotic System Having One or More Tunable Actuator Joint Modules Comprising A Quasi-Passive Elastic Actuator

ABSTRACT

A tunable actuator joint module of a robotic assembly comprises an output member and an input member, where the output member is rotatable about an axis of rotation. A primary actuator (e.g., a motor) is operable to apply a torque to rotate the output member about the axis of rotation. A quasi-passive elastic actuator (e.g., rotary or linear pneumatic actuator) comprising an elastic component is tunable to a joint stiffness value and is operable to selectively release stored energy to apply an augmented torque to assist rotation of the output member and to minimize power consumption of the primary actuator. The tunable actuator joint module comprises a control system having a valve assembly controllably operable to switch the quasi-passive elastic actuator between an elastic state and an inelastic state during respective portions of movement of the robotic assembly (e.g., a hip or knee joint of an exoskeleton). Associated systems and methods are provided.

RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.15/810,108, filed Nov. 12, 2017, entitled “Tunable Actuator JointModules Having Energy Recovering Quasi-Passive Elastic Actuators for Usewithin a Robotic System” which claims the benefit of U.S. ProvisionalApplication Ser. No. 62/421,175, filed Nov. 11, 2016, and entitled,“Tunable Energy Recovering Quasi-Passive Actuators” each of which isincorporated by reference in its entirety herein.

BACKGROUND

A wide variety of exoskeleton, humanoid, robotic arms, and other robotsand robotic systems exist, many of which seek the most efficientoperation possible. One fundamental technical problem that continues tobe a focus is how such systems, such as where energetic autonomy isconcerned, can minimize power consumption while still providingacceptable levels of force output. Indeed, power remains an inevitablechallenge in the world of robotics. Designers of such systems typicallyattempt to optimize operation based on the intended use or application.In many cases, either power or efficiency is sacrificed, at least tosome extent. For instance, some robotic systems employ high-output powersystems that can meet the force output demands of the robotic system,putting this ahead of any efficiency considerations. On the other hand,some robotic systems employ more efficient power systems in an attemptto improve efficiency, with force output being a secondaryconsideration. High output force or power systems, while capable ofperforming various tasks, can be costly. Moreover, such systems oftenare tethered to a power source as portable power remains limited in itscapabilities. Efficient, yet low force output systems can lackpracticality, inasmuch as many robotic systems are designed to assisthumans in work related or other tasks that require a certain level offorce in order to perform the task(s). Overall, the power issue has beena challenging obstacle with various efforts being made to maximizeoutput while minimizing power consumption. Even small advances in thisratio of power to output energy consumption area can be highlybeneficial. While much research and development is ongoing to improvepower sources, another way robotic systems can improve the power toenergy output ratio is through the structural build of the roboticsystem, namely the way various components are configured, how these arecontrolled, and if the systems can take advantage of naturally occurringphenomenon, such as gravity.

BRIEF SUMMARY OF THE INVENTION

An initial summary of the disclosed technology is provided here.Specific technology examples are described in further detail below. Thisinitial summary is intended to set forth examples and aid readers inunderstanding the technology more quickly, but is not intended toidentify key features or essential features of the technology nor is itintended to limit the scope of the claimed subject matter.

The present disclosure sets forth a tunable actuator joint module of arobotic assembly comprising an output member operable to couple to afirst support member of a robotic system, and an input member operableto couple to a second support member of a robotic system. The tunableactuator joint module comprises a primary actuator operable to apply atorque to rotate the output member about an axis of rotation. Thetunable actuator joint module comprises a quasi-passive elastic actuatorcomprising an elastic component dynamically tunable to a joint stiffnessvalue. The quasi-passive elastic actuator is operable to selectivelystore energy upon a first rotation of the input member, and operable toselectively release energy upon a second rotation of the input member toapply an augmented torque that combines with the torque from the primaryactuator to assist rotation of the output member during the secondrotation. For example, the quasi-passive elastic actuator can operate inparallel with a primary actuator, such as a motor, wherein thequasi-passive elastic actuator provides the ability to disengage theelastic component (i.e., spring or device/mechanism that exhibitsspring-like behavior) during the free swing phase of a gait cycle, butengage the elastic component during certain strategically selectiveportions of the support phases of the gait cycle (or during othermotions of a robotic system) where energy capture and recovery can beexploited to reduce energy in the tunable actuator joint module in theform of reducing primary motor torque and power consumptionrequirements. In one aspect, the elastic component can comprise apneumatic gas spring element with active shunting provided by aninternal valve assembly (a shunt circuit of the quasi-passive elasticactuator) that provides a lightweight solution for energy recovery byway of its adjustable stiffness (via gas pressure charge) and by way ofactive engagement and disengagement of its shunt circuit (e.g. via asolenoid or voice-coil actuated valve).

In one example, the tunable actuator joint module comprises or isotherwise operable with a control system operatively coupled to thequasi-passive elastic actuator for selectively controlling applicationof the augmented torque. In one example, the control system comprises avalve assembly operable to switch the quasi-passive elastic actuatorbetween an elastic state and an inelastic state (i.e., disengaging(closing) and engaging (opening) the shunt circuit, respectively).

In one example, the valve assembly comprises a valve device actuatableto allow or restrict fluid (e.g., air or other gaseous liquids) flowbetween compression and expansion chambers (gas chambers) of thequasi-passive elastic actuator. In one example, the valve device of thevalve assembly is disposed through an opening of a first vane or vanedevice, wherein the valve device is controllable to open and close theshunt circuit and switch the quasi-passive elastic actuator between theinelastic and elastic states, respectively.

In one example, the quasi-passive elastic actuator, and particularly theelastic component, can comprise a rotary pneumatic actuator. In anotherexample, the quasi-passive elastic actuator can comprise a linearpneumatic actuator. It is noted that the pneumatic actuators cancomprise air or any other suitable gas (e.g., nitrogen) as recognized bythose skilled in the art. In each of these examples, the elasticcomponent can comprise a housing that is gas pressure charged with aselected gas pressure to define a predefined joint stiffness value.

In one example, the primary actuator can comprise an electric motor thatcan be operable with a planetary drive transmission rotatably coupled tothe electric motor. The planetary drive transmission can be at leastpartially disposed within a central void of the primary actuator (e.g.,electric motor). In one example, a transmission belt can be rotatablycoupled between an output pulley of the primary actuator and an inputpulley of the rotary pneumatic actuator.

The present disclosure further sets forth a robotic system for a roboticlimb configured to recover energy for minimizing power consumption ofthe robotic system. The system can comprise a plurality of supportmembers and a plurality of tunable actuator joint modules at variousjoints of the robotic system, each of which can be rotatably coupled totwo of the plurality of support members to define a joint of the roboticsystem. Each tunable actuator joint module comprises: an axis ofrotation, the joint defining a degree of freedom; a primary actuatoroperable to apply a primary torque to cause actuation of the joint; anda quasi-passive elastic actuator comprising an elastic componentdynamically tunable to a joint stiffness value and selectivelycontrollable between an elastic state and an inelastic state, thequasi-passive actuator being adapted or operable to store energy upon afirst rotation of the joint, and to release energy upon a secondrotation of the joint to apply an augmented torque to the joint thatcombines with the primary torque from the primary actuator to assistrotation of the joint and to minimize power consumption of the primaryactuator.

The present disclosure further sets forth a method for operating arobotic system comprising at least one tunable joint module. The methodcomprises: causing a first rotation of a tunable actuator joint moduleof a robotic assembly; engaging a quasi-passive elastic actuator of thetunable joint module during the first rotation to store energy;actuating the primary actuator to apply a primary torque and cause asecond rotation of the tunable actuator joint module in a differentdirection from the first rotation, the quasi-passive actuator releasingthe stored energy and applying an augmented torque to the primary torqueduring the second rotation, thereby reducing the power needed by theprimary actuator to apply the primary torque to cause the secondrotation. The states of the quasi-passive elastic actuator can becontrolled by a control system comprising a valve assembly thatregulates and controls the flow of gasses within the quasi-passiveelastic actuator.

The method can further comprise operating a valve assembly of thecontrol system to engage or open a shunt circuit to selectivelydisengage operation of the quasi-passive elastic actuator (it enters theinelastic state) of the tunable actuator joint module, and to disengageor close the shunt circuit to engage operation of the quasi-passiveelastic actuator in the elastic state.

The method can further comprise actuating a valve device of the valveassembly to open and close the valve assembly (and open or close theshunt circuit).

The method can further comprise generating a predetermined jointstiffness value by gas pressure charging the tunable actuator jointmodule to a desired or predetermined gas pressure.

The method can further comprise pre-charging the quasi-passive actuatorand compressing the elastic component, wherein the stored energy thereincan be released at a given time to apply the augmented torque.

The method can further comprise dynamically modifying the predeterminedjoint stiffness value by changing the gas pressure in the housing.

The present disclosure further sets forth a method of making a tunableactuator joint module. The method comprises configuring a primaryactuator, such as a motor, to apply a primary torque about an axis ofrotation of a joint of a robotic system to facilitate actuation of thejoint within a robot or robotic system about an axis of rotation, andconfiguring a quasi-passive elastic actuator to be operable with theprimary actuator. The quasi-passive elastic actuator can comprise anelastic component dynamically tunable to a joint stiffness value, thequasi-passive elastic actuator being operable to selectively storeenergy upon a first rotation of the joint, and operable to selectivelyrelease energy upon a second rotation of the joint to apply an augmentedtorque to the primary torque to assist rotation of the joint during thesecond rotation.

The method can further comprise operably coupling a valve assembly tothe quasi-passive elastic actuator. In one example, a valve device canbe disposed through an opening of the elastic component in the form of afirst vane or vane device. The valve device can be actuatable to allowor restrict gas flow between compression and expansion chambers of thequasi-passive elastic actuator.

The method can further comprise configuring the elastic element withcompression and expansion chambers. In one example, the compression andexpansion chambers can comprise equal volumes. In another example, thecompression and expansion chambers can comprise disparate volumes. Instill another example, the compression chamber volume can be greaterthan the expansion chamber volume.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the invention will be apparent from thedetailed description which follows, taken in conjunction with theaccompanying drawings, which together illustrate, by way of example,features of the invention; and, wherein:

FIG. 1 illustrates two positions of a robotic assembly in the form of alower portion of an exoskeleton having at least one tunable actuatorjoint module in accordance with an example of the present disclosure;

FIG. 2A is a schematic illustration of a tunable actuator joint modulein accordance with an example of the present disclosure;

FIG. 2B is a schematic illustration of a tunable actuator joint modulein accordance with an example of the present disclosure;

FIG. 3A is a graph illustrating human weight normalized knee jointtorque vs. knee joint angle of a human gait cycle;

FIG. 3B is a graph illustrating the torque required to accomplish ajoint trajectory and a portion of a gait where an elastic response canbe created by a tunable actuator joint module in accordance with anexample;

FIG. 3C is a graph illustrating performance of a tunable actuator jointmodule in accordance with an example;

FIG. 4A is an isometric view of a robotic assembly, namely a wearablerobotic exoskeleton, having at least one tunable actuator joint modulein accordance with an example of the present disclosure;

FIG. 4B is an isometric view of the robotic assembly of FIG. 4A;

FIG. 5A is a partial isometric view a tunable actuator joint module fora knee joint of the robotic assembly of FIG. 4A in accordance with anexample of the present disclosure;

FIG. 5B is a partial isometric view of the tunable actuator joint moduleof FIG. 5A from another perspective;

FIG. 6A is an isometric view of a tunable actuator joint module operablewith the robotic assemblies of FIG. 1 or 4A, in accordance with anexample of the present disclosure;

FIG. 6B is an isometric view of the tunable actuator joint module ofFIG. 6A in an actuated position;

FIG. 6C is a front view of the tunable actuator joint module of FIG. 6A;

FIG. 6D is a left side view of the tunable actuator joint module of FIG.6A;

FIG. 7A is a partially exploded view of the tunable actuator jointmodule of FIG. 6A;

FIG. 7B is a partially exploded rear view of the tunable actuator jointmodule of FIG. 6A;

FIG. 8A is a partially exploded view of the tunable actuator jointmodule of FIG. 6A;

FIG. 8B is a partially exploded front view of the tunable actuator jointmodule of FIG. 6A;

FIG. 9A is an exploded view of the primary actuator of the tunableactuator joint module of FIG. 6A;

FIG. 9B is a partially exploded front view of the primary actuator ofthe tunable actuator joint module of FIG. 6A;

FIG. 10A is an exploded view of the quasi-passive elastic actuator ofthe tunable actuator joint module of FIG. 6A;

FIG. 10B is a partially exploded front view of the quasi-passive elasticactuator of the tunable actuator joint module of FIG. 6A;

FIG. 11A is a cross-sectional view of the quasi-passive elastic actuatorof the tunable actuator joint module of FIG. 6A taken along lines 11A inFIG. 10B;

FIG. 11B is a cross-sectional view of the quasi-passive elastic actuatorof the tunable actuator joint module of FIG. 6A taken along lines 11A inFIG. 10B, but shown in a rotated state;

FIG. 12A is an isometric view of a the tunable actuator joint moduleoperable with the robotic assembly of FIG. 4A in accordance with anexample of the present disclosure;

FIG. 12B is an isometric view the tunable actuator joint module of FIG.12A;

FIG. 12C is an isometric view the tunable actuator joint module of FIG.12A;

FIG. 12D is a partial exploded view the tunable actuator joint module ofFIG. 12A;

FIG. 12E is an isometric view of the quasi-passive elastic actuator ofthe tunable actuator joint module of FIG. 12A;

FIG. 12F is an isometric rear view of the quasi-passive elastic actuatorof the tunable actuator joint module of FIG. 12A;

FIG. 13A is an isometric view of a tunable actuator joint moduleoperable with the robotic assemblies of FIGS. 1 and 4A in accordancewith an example of the present disclosure;

FIG. 13B is a cross-sectional view of the tunable actuator joint moduleof FIG. 13A taken along lines 13B of FIG. 31A;

FIG. 14A is an isometric view of a first vane device and a second vanedevice of a quasi-passive elastic actuator of a tunable actuator jointmodule operable with the any one of the tunable actuator joint modulesof FIGS. 5A, 6A, 12A, and 13A, in accordance with an example of thepresent disclosure;

FIG. 14B is an isometric view of the first vane device and the secondvane device of FIG. 14A from another perspective;

FIG. 15A is a cross-sectional view of a valve assembly operable with thefirst vane device of FIG. 14A in accordance with an example of thepresent disclosure;

FIG. 15B is a schematic cross-sectional front view of the valve assemblyof FIG. 15A operable with the first vane device and the second vanedevice of FIG. 14A, with the shunt circuit open, in accordance with anexample of the present disclosure;

FIG. 15C schematic cross-sectional front view of the valve assembly ofFIG. 15A operable with the first vane device and the second vane deviceof FIG. 14A, with the shunt circuit closed;

FIG. 16A is a cross sectional view (y-plane) of a first vane device(e.g., FIG. 14A) which forms part of a valve assembly in accordance withan example of the present disclosure;

FIG. 16B is a cross sectional view (x-plane) of the first vane device ofFIG. 16A;

FIG. 17A is a cross sectional view of a valve assembly operable with thefirst vane device of FIG. 14A in accordance with an example of thepresent disclosure;

FIG. 17B is an exploded view of the valve assembly of FIG. 17A;

FIG. 17C is an exploded right view of the valve assembly of FIG. 17A;

FIG. 17D is a cross-sectional view of the valve assembly, in an openposition, of FIG. 17A;

FIG. 17E is a cross-sectional view of the valve assembly, in a closedposition, of FIG. 17A;

FIG. 18A is an isometric view of a valve assembly operable with thefirst vane device of FIG. 14A in accordance with an example of thepresent disclosure;

FIG. 18B is an exploded view of the valve assembly of FIG. 18A;

FIG. 18C is a cross-sectional view of the valve assembly, in an openposition, of FIG. 18A;

FIG. 18D is a cross-sectional view of the valve assembly, in a closedposition, of FIG. 18A;

FIG. 19 is a graph illustrating performance values for joint dampingtorque vs. various rotor vane conduit sizes in accordance with anexample of the present disclosure;

FIG. 20A is an isometric view of a tunable actuator joint moduleoperable with the robotic assemblies of FIGS. 1 and 4A in accordancewith an example of the present disclosure;

FIG. 20B is a right side view of the tunable actuator joint module ofFIG. 20A;

FIG. 20C is an isometric view of the tunable actuator joint module ofFIG. 20A in an elastic state;

FIG. 20D is a cross-sectional view of an upper section of a portion ofthe tunable actuator joint module FIG. 20A, showing a valve assembly inan open position;

FIG. 20E is a cross-sectional view of an upper portion of the tunableactuator joint module of FIG. 20A, showing the valve assembly in aclosed position;

FIG. 20F is a cross-sectional view of a lower portion of the tunableactuator joint module of FIG. 20A; and

FIG. 21 is a schematic view of a remotely located quasi-passive elasticactuator operable with the robotic assemblies of FIGS. 1 and 4A inaccordance with an example of the present disclosure.

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

DETAILED DESCRIPTION

As used herein, the term “substantially” refers to the complete ornearly complete extent or degree of an action, characteristic, property,state, structure, item, or result. For example, an object that is“substantially” enclosed would mean that the object is either completelyenclosed or nearly completely enclosed. The exact allowable degree ofdeviation from absolute completeness may in some cases depend on thespecific context. However, generally speaking the nearness of completionwill be so as to have the same overall result as if absolute and totalcompletion were obtained. The use of “substantially” is equallyapplicable when used in a negative connotation to refer to the completeor near complete lack of an action, characteristic, property, state,structure, item, or result.

As used herein, “adjacent” refers to the proximity of two structures orelements. Particularly, elements that are identified as being “adjacent”may be either abutting or connected. Such elements may also be near orclose to each other without necessarily contacting each other. The exactdegree of proximity may in some cases depend on the specific context.

One example of a robotic assembly 100 is generically illustrated inFIG. 1. The robotic assembly 100 is shown in the form of an exoskeleton,and particularly a lower exoskeleton wearable by a user about the lowerbody. However, this is not intended to be limiting in any way as theconcepts discussed herein can be applicable to and incorporated into orimplemented with various types of robotic devices, such as exoskeletons(both upper and lower exoskeletons), humanoid robots or robotic devices,teleoperated robots or robotic devices, robotic arms, unmanned groundrobots or robotic devices, master/slave robots or robotic devices(including those operable with or within a virtual environment), and anyother types as will be apparent to those skilled in the art.

In the example of the robotic assembly 100, the exoskeleton as disclosedherein can be configured as a full-body exoskeleton (i.e., similar tothe exoskeleton having both a lower body portion and upper body portion,see FIG. 4A), or as only a lower body exoskeleton (i.e., some or all ofthe lower body portion), or as only an upper body exoskeleton (i.e.,some or all of the upper body portion).

The robotic assembly 100 can comprise a plurality of tunable actuatorjoint modules having a quasi-passive elastic actuator. The upperextremity quasi-passive elastic actuators can have a different functionfrom the lower extremity quasi-passive elastic actuators, or they canfunction similarly. For example, the lower extremity quasi-passiveelastic actuators can provide an energy recovery mechanism during aportion of cyclic motions such as walking or running, and an ability toswing freely during other parts of the cycle or for other activities.Upper extremity quasi-passive elastic actuators can provide passivegravity compensation when the arms are raised to support armor and/orweapon masses. In both cases, the quasi-passive elastic actuatorsfunction to reduce the demand on the power supply, and on the primaryactuators that may be used to do work in parallel with the quasi-passiveelastic actuators. It is noted that, in example robotic systems, such asthose described herein, the types of quasi-passive actuators used withinthe different joints and corresponding tunable actuator joint modulescan be the same or different. Using the example of the robotic assembly100, different quasi-passive elastic actuators can be used between theupper and lower extremities of the robotic system 100, or between thevarious tunable actuator joint modules within the upper extremity (thesame being the case with the lower extremity), or between varioustunable actuator joint modules within the same limb.

The example elastic actuators described herein can be referred to asquasi-passive elastic actuators as they are operable in active andinactive states or modes of operation (as compared to being entirelypassive elastic actuators that are always either storing energy orreleasing energy during all rotational movements of a joint, or othermovements of a mechanical system). In examples discussed herein, thepassive and inactive modes or states of operation can be selectable orcontrollable and even dynamically selectable or controllable (e.g.,selectable in real-time), as well as repeatedly switched from one stateor mode to another state or mode, during operation of the roboticsystem. Depending upon the configuration of the tunable actuator jointmodule, example quasi-passive elastic actuators can comprise a firstactive state (sometimes referred to herein as an elastic state) in whichthe quasi-passive elastic actuator can be actuated to store and releaseenergy during various rotations of a joint of the robotic system, asecond passive state (sometimes referred to herein as an inelasticstate) in which the quasi-passive elastic actuator can be made inactive,such that energy is neither stored nor released during various rotationsof the joint, and in some cases a third semi-active or partially activestate (sometimes referred to herein as a semi-elastic state) in whichthe quasi-passive elastic actuator can be partially actuated to storeand release energy during various rotations of the joint. In someexample robotic systems, the quasi-passive elastic actuator can beswitchable between the different modes or states of operation as neededor desired depending on, for example, needed or desired tasks andcorresponding rotation movements, various torque or load requirements ofthe one or more joints of the robotic system, or needed or desiredbraking forces.

In some examples, the robotic assembly 100 can comprise left and rightexoskeleton limbs (note that only the right exoskeleton limb 102 isshown in FIG. 1). The exoskeleton limb 102 can comprise a plurality ofsupport members 104 a-d (e.g., the rigid, structural supports thatextend between the joints within the limb of the exoskeleton, or thatlink the joints together, much like the bones in the human bodyextending between the joints). The support members 104 a-d can becoupled together for relative movement about a plurality of joints, suchas tunable actuator joint modules 106 a-d, defining a plurality ofdegrees of freedom about respective axes of rotation 108 a-d. Therotational degrees of freedom about the axes of rotation 108 a-d cancorrespond to one or more degrees of freedom of the human leg. Forexample, the rotational degrees of freedom about the axes 108 a-d cancorrespond, respectively, to hip abduction/adduction, hipflexion/extension, knee flexion/extension, and ankle flexion/extension,respectively. Similarly, although not shown, degrees of freedom aboutrespective axes of rotation within an upper body exoskeleton cancorrespond to one or more degrees of freedom of a human arm. Forexample, the degrees of freedom about the axes of rotation cancorrespond to shoulder abduction/adduction, shoulder flexion/extension,shoulder medial/lateral rotation, elbow flexion/extension, wristpronation/supination, and wrist flexion/extension. A degree of freedomcorresponding to wrist abduction/adduction can also be included, asdesired.

A human user or operator may use or interact with the exoskeletonrobotic assembly 100 (or 101 of FIG. 4A) by interfacing with the roboticassembly 100. This can be accomplished in a variety of ways as is knownin the art. For example, an operator may interface with the roboticassembly 100 by placing his or her foot into a foot portion of theassembly, where the foot of the operator can be in contact with acorresponding force sensor. Portions of the human operator can also bein contact with other force sensors of the exoskeleton robotic assembly100 located at various locations of the robotic assembly 100. Forexample, a hip portion of the robotic assembly 100 can have one or moreforce sensors configured to interact with the operator's hip. Theoperator can be coupled to the robotic assembly 100 by a waist strap orother appropriate coupling device. The operator can be further coupledto the robotic assembly 100 by a foot strap or other securing mechanism.In one aspect, various force sensors can be located about a hip, knee orankle portion of the robotic assembly 100, corresponding to respectiveparts of the operator. While reference is made to sensors disposed atspecific locations on or about the robotic assembly 100, it should beunderstood that position or force sensors, or both, can be strategicallyplaced at numerous locations on or about the robotic assembly 100 inorder to facilitate proper operation of the robotic assembly 100.

As a general overview, tunable actuator joint modules 106 a-d can beassociated with various degrees of freedom of the exoskeleton to provideforces or torques to the support members in the respective degrees offreedom. Unlike traditional exoskeleton systems and devices, the roboticassembly 100 can be configured, such that each tunable actuator jointmodule is configured to recover energy, which can reduce complexity andpower consumption of the robotic assembly 100. For example, the tunableactuator joint module 106 c, which defines a degree of freedomcorresponding to a degree of freedom of knee flexion/extension, can beconfigured to recover energy during a first gait movement and thenrelease such energy during a second gait movement to apply an augmentedtorque to assist a primary actuator providing a primary torque inrotation of the joint about the degree of freedom (and in parallel withthe torque applied by the primary actuator of the tunable actuator jointmodule 106 c, as discussed below). The tunable actuator joint module 106c can be selectively controlled, such that the quasi-passive elasticactuator can be engaged (i.e., caused to enter an operating state orcondition in which the elastic actuator is operable and enabled to storeand release energy (an elastic or semi-elastic state)) and disengagedfrom operation (i.e., caused to enter an operating state or condition orconfiguration where it neither stores nor releases energy (an inelasticstate)) during joint rotation, or where any previously stored energy canbe dissipated or released. In the inelastic state, the joint “freelyswings” with negligible resistance to rotate the joint as the operatorwalks or runs, for instance. By operating in parallel with the primaryactuator (e.g., a primary motor operable to actuate the joint), thequasi-passive elastic actuator can provide or apply an augmented torquein parallel with the torque provided by the primary actuator (i.e., atorque that is added to the torque generated by the primary actuator),or a braking force.

The quasi-passive elastic actuator can comprise a compact internalvalve, such as a two-way valve, that can be controlled and operated tochange the modes of the quasi-passive actuator, namely to switch betweenan elastic state (where the actuator acts as a spring for transientenergy storage and recovery), a semi-elastic state (where the actuatoracts as a spring partially compressed), and an inelastic state (wherethe actuator employs a shunting function that allows the actuator tomove freely (i.e., not to store or release energy) (except for frictionand movement of fluid through the valve). Moreover, the tunable actuatorjoint module 106 c can be “tuned” to comprise a desired stiffness, asfurther discussed below. Thus, the magnitude of stiffness for a givenjoint is adjustable for mission specific payloads and terrain-specificgaits while the active valve controls exactly when that stiffness isengaged for energy recovery during the support phase and when it isdisengaged during the free swinging phase.

The result is effectively a quasi-passive elastic mechanism that, in oneadvantage, is selectively operable to recover energy (e.g., energy lostduring some gait motions) to reduce or minimize power consumptionrequired to actuate the joint. Therefore, when combining a plurality oftunable actuator joint modules within a robotic assembly, such as thelower body exoskeleton shown in FIG. 1, for example, a significantamount of energy can be recovered and utilized during movement (via hip,knee, and ankle joints), which can reduce weight, size, complexity, andoverall power consumption of the exoskeleton. A quasi-passive actuatorfor energy recovery can comprise an elastic component, for example,either a mechanical or pneumatic or hydraulic element, that is capableof storing and releasing energy to the joint, and, optionally, an activeswitch or clutch capable of engaging and disengaging the elasticcomponent from the primary torque source powering the joint. Implicit inthis energy recovery approach is the defining of the magnitude ofelastic stiffness, as well as when to engage and disengage the elasticactuator during each gait cycle. These values can be optimized bysearching for a stiffness, position offset, and temporal window thatminimizes the average of the square of joint torques during the gaitcycle. This numerical optimization, in essence, results in minimumaverage power consumption of a given primary joint torque actuator for agiven gait or maneuver. The practical implementation of this approachfor energy recovery and reduction of joint actuation torque thus leadsto defining that angular stiffness which best works for the majority oftime that the robotic assembly is to be used, e.g., walking vs. running,and establishing gait recognition algorithms that can be used toprecisely engage and disengage the elastic actuator(s) over a broadrange of activities.

The above general overview is explained in more detail below.

FIGS. 2A and 2B each schematically illustrate tunable actuator jointmodules in accordance with two examples of the present disclosure. FIG.2A shows a tunable actuator joint module 120 having a primary actuator122 operable to provide a primary torque to the tunable actuator jointmodule 120. In one example, the primary actuator can comprise a gearedmotor (e.g., a primary actuator having an electric motor operable with atransmission, such as a planetary type of transmission (or any othertype of transmission as will be appreciated by those skilled in theart), the primary actuator 122 operating in parallel with aquasi-passive elastic actuator 124 (e.g., a rotary or linear pneumatic(air or other gas) actuator, as will be discussed below), both operableto apply a torque, and in some states a torque in parallel, to a load(e.g., a torque to rotate a joint, or the support members rotatableabout one another defining a joint, of a robotic assembly, as in FIGS. 1and 4A).

The quasi-passive elastic actuator 124 can comprise a valve assembly126, such as further described below regarding FIGS. 14A-19. The valveassembly 126 can facilitate or can comprise at least part of a controlsystem for the tunable actuator joint module 120, such that it iscontrollable to selectively facilitate the application of the augmentedtorque via the quasi-passive fluid actuator 124 in parallel with thetorque applied by the geared motor 122.

In examples described herein, “selective” can mean that the tunableactuator joint module can be controlled in real-time at select times andfor select durations as needed or desired, such as to vary a magnitudeand timing of a braking force, vary a magnitude and timing ofcompression of the elastic component of the quasi-passive actuator andthe storing and releasing of energy therein, or vary a magnitude andtiming of a primary torque generated by the primary actuator dependingupon different operating conditions, operating states, different demandsof the robotic system, or as desired by the operator. Selective controlcan mean that the quasi-passive elastic actuator can be operated inconjunction with the primary actuator all or some of the time or for adesired duration of time. In addition, “selective” can mean, inexamples, that one or more operating parameters or the outputperformance of the valve assembly can be controlled and varied inreal-time as needed or desired. Operating parameters or outputperformance can include, but is/are not limited to, a magnitude of theaugmented torque to be applied, a magnitude of the braking forcegenerated, the stiffness or elasticity of the elastic actuator, the zeroor null point of actuation of the elastic actuator, and others.

In examples where the quasi-passive actuator is caused to enter asemi-elastic state or mode of operation, the quasi-passive elasticactuator can be actuated to partially compress the elastic or springcomponent of the quasi-passive elastic actuator to store, and be enabledto release, an amount of energy or enabled to generate a magnitude of abraking force that is less than what would otherwise be achieved if thequasi-passive elastic actuator were in a fully elastic state. Statedanother way, semi-elastic describes that state in which there is a lessthan 1:1 transfer of energy or forces, due to rotation of the joint, tothe quasi-passive elastic actuator coupled between the input and outputmembers (e.g., because the valve assembly is partially open).“Semi-elastic,” as used herein, is not intended to refer to the inherentelastic property (i.e., the elasticity) of the elastic component of thequasi-passive elastic actuator, but merely to a degree of compression ofthe elastic component.

FIG. 2B is similar to FIG. 2A, except that in this example of a tunableactuator joint module 120′, the primary actuator 122′ comprises ahydraulic actuator incorporated as a powered actuator to operate inparallel with the quasi-passive fluid actuator 124′ of the tunableactuator joint module 120′.

FIG. 3A is a graph showing joint torque vs. joint position as theseoccur during an example gait of a human, the graph showing the torque(N-m/kg) occurring in the joint relative to or as corresponding to theangle of rotation of the joint. This particular graph is illustrative ofan example torque/angular rotation relationship of a human knee (withoutwearing an exoskeleton), while walking approximately 3 mph on a flatsurface. A first gait movement from point A to point B illustratesstance compression following heel strike, a second gait movement frompoint B to C illustrates stance extension, with the stance phase beingcompleted at point D. A third gait movement between points D, E, F, andA illustrates “double support and leg swing.” Therefore, the “stancephase” is from heel strike (point A) to toe-roll/terminal stance (pointsA to D), where the torque-joint profile has a quasi-elastic behavior(walking and running are similar regarding this quasi-elasticstiffness). During this phase, the knee also acts as a shock absorber.The “swing phase” is from toe-off to heel strike (points E to A), andduring this phase the knee exhibits a quasi-ballistic (passive dynamics)response with some damping during the final extension that occurs beforeheel strike (thus, the knee acts as a controlled damper or shockabsorber).

This characteristic of the human gait is not unique to the knee joint,nor limited to the walking gait, and forms the basis for the tunableactuator joint modules discussed herein. Indeed, when reviewing thejoint torque vs. position plots of simulated cyclical exoskeletonactivities, such as walking, running, and step climbing, there areperiods of time during these specific gait motions where elastic energyrecovery can be exploited to reduce the requirement for motor torque torun the joint. Thus, the tunable actuator joint modules described hereincan be configured to exploit the features of the natural motion of thehip, knee, and ankle, for instance, to minimize demands on poweredactuators (e.g., electric-geared motors) to reduce overall powerconsumption within the robotics assembly. The tunable actuator jointmodules discussed herein can also be incorporated into shoulder andelbow joints, for instance, but these may be more task-specific than aswith the lower body joints, as further discussed below. However, thetunable actuator joint modules of lower joints (e.g., hip, knee, ankle)can also be configured to operate based on a specific task (e.g.,lifting a load, sitting and standing, and others), rather than just acyclical operation (e.g., walking or running).

FIG. 3B is a graph showing an exoskeleton knee joint torque (N-m) vs.position (deg.) for walking at 3.5 mph with a 50 lb. payload. Theplotted “triangular” labeled line (“joint actuation torque”) representsthe required overall torque to accomplish the prescribed jointtrajectory, while the plotted “circular” labeled lines (“spring reactiontorque”) represents the part of the gait where an elastic response canby created by a quasi-passive elastic actuator of a tunable actuatorjoint module. Thus, this spring reaction torque can be exploited toreduce power consumption to actuate a joint, as further detailed below.

FIG. 3C is a graph illustrating performance of an exoskeleton having atunable actuator joint module with a quasi-passive elastic actuatoroperating in parallel with a primary actuator, the joint module having ajoint stiffness of 7 N-m/degree, associated with the human knee joint,in one example. More specifically, the graph shows joint torque (N-m)vs. joint speed (deg./sec) for walking at 3.5 mph with a 50 lb. payload.The plotted “triangular” labeled line (“joint actuation torque”)represents the required overall torque to accomplish the prescribedjoint trajectory (e.g., the torque required to rotate a knee), while theplotted “circular” labeled lines (“spring reaction torque”) representsthe part of the gait where an elastic response can be created byengaging and disengaging the quasi-passive elastic actuator in a timelymanner, as exemplified herein.

As illustrated by this “circular” labeled line, the resulting peaktorque is substantially reduced (approximately 25 N-m) vs. thenormalized torque requirement (approximately 100 N-m) of the“triangular” labeled line. That is, normally (i.e., withoutincorporating a tunable actuator joint module having an elasticactuator) the torque requirement is peaked at approximately 100 N-m;however, when incorporating a tunable actuator joint module having anelastic actuator as disclosed herein, the resulting peak torque can beonly approximately 20 N-m, thus significantly reducing powerrequirements for the same gait cycle and operating conditions. This isbecause the tunable actuator joint module stores energy during a firstgait movement (via the quasi-passive elastic actuator), and thenreleases that energy during a second gait movement to apply an augmentedtorque that can be applied in parallel with a torque applied by aprimary actuator (e.g., a geared motor) of the tunable actuator jointmodule. Of course, other factors play a role in these results, such asweight, payload, etc. In any event, these graphs illustrate that muchless on-board power is required by the powered motor to appropriatelyactuate a joint when used in conjunction with a selectively controllablequasi-passive elastic actuator, as further exemplified below. The use ofa parallel elastic actuator effectively reduces the requirement formotor torque as the elastic actuator is engaged and disengaged in atimely manner, such as during specific phases of a gait cycle. Similarplots or graphs can be shown for hip joints, ankle joints, shoulderjoints, and elbow joints. In some cases, the elastic actuator can beengaged full-time for the gaits of these joints.

For the sake of clarity, FIGS. 4A-5B and FIGS. 12A-12F pertain to afirst example of a tunable actuator joint module (comprising aquasi-passive elastic actuator in the form of a rotary pneumaticactuator having a rotary pneumatic spring as the elastic component, thequasi-passive actuator being operable in an elastic state, asemi-elastic state, and an inelastic state). FIGS. 6A-11B pertain to asecond example of a tunable actuator joint module (comprising aquasi-passive elastic actuator in the form of a rotary pneumaticactuator having a rotary pneumatic spring as the elastic component, thequasi-passive actuator being operable in an elastic state, asemi-elastic state, and an inelastic state). FIGS. 13A and 13B pertainto a third example of a tunable actuator joint module (comprising aquasi-passive elastic actuator in the form of a rotary pneumaticactuator having a rotary pneumatic spring as the elastic component, thequasi-passive actuator being operable in an elastic state, asemi-elastic state, and an inelastic state). FIGS. 14A-15C pertain to anexample of a first vane or vane device and a second vane or vane deviceoperable with each of said first, second, and third example tunableactuator joint modules, as well as the case with the example first vanedevice of FIGS. 16A and 16B. FIGS. 17A-17E pertain to one example of avalve assembly operable with the first vane device of FIGS. 16A and 16B.Similarly, FIGS. 18A-18D pertain to another example of a valve assemblyoperable with the first vane device of FIGS. 16A and 16B. Finally, FIGS.20A-20F pertain to another example of a tunable actuator joint module(comprising a quasi-passive elastic actuator in the form of a linearpneumatic actuator having a linear pneumatic spring as the elasticcomponent, the quasi-passive actuator being operable in an elasticstate, a semi-elastic state, and an inelastic state). The followingdiscussion will cross-reference relevant Figures accordingly.

FIGS. 4A and 4B show isometric views of an exemplary robotic assembly101 in the form of an exoskeleton wearable or usable by a humanoperator. The robotic assembly 101 could alternatively be a humanoidrobot, or other robotic assembly as discussed above. As shown, therobotic assembly 101 can be configured as a full-body exoskeleton (i.e.,an exoskeleton having both a lower body portion and an upper bodyportion). However, this is not intended to be limiting as theexoskeleton can comprise only a lower body exoskeleton (i.e., some orall of the lower body portion), or only an upper body exoskeleton (i.e.,some or all of the upper body portion).

The robotic assembly 101 can comprise left and right exoskeleton limbs.The right exoskeleton limb 103 can comprise a plurality of lower bodysupport members 105 a-d. The support members 105 a-c can be coupledtogether for relative movement about a plurality of respective joints107 a-c defining a plurality of degrees of freedom about respective axesof rotation. The right knee joint 107 c can comprise a tunable actuatorjoint module 109 a having a quasi-passive elastic actuator, as describedherein. It will be appreciated, although not detailed herein, that thehip joint 107 a can also comprise a tunable actuator joint module havinga quasi-passive elastic actuator, as described herein. The ankle joint107 d can also comprise a tunable actuator joint module, such asdescribed below regarding FIGS. 20A-20F. The left exoskeleton limb canbe similarly configured, as shown.

FIGS. 5A and 5B show close up, partial front and rear perspective viewsof the tunable actuator joint module 109 a of FIG. 4A (with the supportmember 105 b that supports the tunable actuator joint module 109 a beinghidden; but see FIGS. 4A and 4B, 12A and 12B). The particular tunableactuator joint module 109 a of FIG. 5A will be specifically describedregarding FIGS. 12A-12F.

The robotic assembly 101 of FIGS. 4A-5B can have the same or similarfeatures as described generally with reference to FIG. 1. For example,the tunable actuator joint module 109 a, which defines a degree offreedom corresponding to extension/flexion of a knee joint, can beconfigured to recover energy during a first gait movement and thenrelease such energy during a second gait movement to apply an augmentedtorque to rotate the knee joint about the degree of freedom in parallelwith a torque applied by a primary actuator of the tunable actuatorjoint module 109 a, similarly as discussed above. Moreover, the tunableactuator joint module 109 a can be selectively controlled to bedisengaged from operation (i.e., inelastic by neither storing norreleasing energy) via a control system (e.g., a valve assembly), suchthat the joint “freely swings” with negligible resistance to rotate thejoint as the operator walks or runs, for instance. And similarly, thetunable actuator joint module 109 a can be “tuned” to define apredefined joint stiffness value, as further discussed below.

FIGS. 6A-11B illustrate various aspects of a tunable actuator jointmodule 130 according to an example of the present disclosure, which canbe incorporated into a robotic assembly or system to comprise and definea joint as discussed herein. Although the tunable actuator joint module130 in the present disclosure will be specifically focused as providinghip and/or knee joints of a robotic assembly this is not intended to belimiting in any way as those skilled in the art will recognize thatsimilar concepts can be incorporated into a tunable actuator jointmodule configured for use in a different joint of the robotic system.For instance, the tunable actuator joint module 130 can readily beincorporated as the module 109 a of FIG. 4A, with slight modification ofthe output member, as discussed below. Note that the tunable actuatorjoint module 130 is shown inverted for purposes of illustration clarity,yet it would readily be incorporated in the orientation as exemplifiedby the tunable actuator joint module 109 a of FIG. 5A.

The tunable actuator joint module 130 comprises a primary actuator 132and a quasi-passive elastic actuator 134 structurally coupled to eachother, and operable with one another to provide torque to the joint. Aninput member 136 a and an output member 136 b (of the quasi-passiveelastic actuator 134) can each rotate about an axis of rotation 137(e.g., corresponding to an axis of rotation and corresponding degree offreedom of a human joint, such as the knee or hip joint). As shown, boththe input and output members 136 a and 136 b can rotate about the same(collinear) axis of rotation 137; however, this is not meant to belimiting because the input and output members 136 a and 136 b could havedifferent axes of rotation if positioned along different axes ofrotation and operably coupled together. The primary actuator 132 (e.g.,a geared electric motor) is operable to apply a torque to the outputmember 136 b for rotation about the axis of rotation 137, and thequasi-passive elastic actuator 134 (e.g., a rotary pneumatic actuator)is selectively operable to generate a braking force, or to apply anaugmented torque to the output member 136 b along with the torqueapplied by the primary actuator 132 to actuate the joint, such as duringa certain portion of a gait movement.

More specifically, the quasi-passive elastic actuator 134 is operable orcontrollable by a control system (e.g., a valve assembly) to selectivelystore energy or to selectively generate a braking force (in an elasticstate or a semi-elastic state) upon a first rotation of the input member136 a, and to selectively release that energy (while still in theelastic or semi-elastic state) during a second or subsequent rotation ofthe input member 136 a. In the elastic and semi-elastic states, thequasi-passive elastic actuator 134 can be enabled to generate a brakingforce to resist rotation of the joint, or to apply an augmented torqueto the output member in parallel with the torque applied by the primaryactuator 132 (as further detailed below), or both. Those skilled in theart will recognize that these different states of operation of thequasi-passive elastic actuator can entered into during rotation of theinput member, and the joint, that is in the same or a differentdirection.

With respect to the elastic state of the quasi-passive actuator as itoperates to store and release energy, in one aspect, the first rotationof the input member 136 a can be achieved via active actuation of theprimary actuator to actuate the tunable joint module and to causerotation of the joint module (and any structural supports coupledthereto). In another aspect, the first rotation of the input member 136a can be achieved passively, namely by exploiting any availablegravitational forces or external forces acting on the robotic systemsuitable to effectuate rotation of the input member 136 b within thetunable actuator joint module (e.g., such as a lower exoskeleton beingcaused to perform a sitting or crouching motion, which therefore affectsrotation of the various tunable joint modules in the exoskeleton). Theexploiting of such gravitational forces by the quasi-passive actuator inparallel with a primary actuator provides the tunable joint module withcompliant gravity compensation. Once the energy is stored, it can bereleased in the form of an augmented torque to the output member 136 b,or it can be used to brake or restrict further rotation.

The quasi-passive elastic actuator 134 can further be configured, upon athird or subsequent rotation(s), to neither store nor release energy,the quasi-passive elastic actuator 134 being caused to enter aninelastic state. In this inelastic state, the input and output members136 a and 136 b are caused to enter a “free swing” mode relative to eachother, meaning that negligible resistance exists about the quasi-passiveelastic actuator 134 (this is so that the actuator 134 does not exhibita joint stiffness value that would restrict rotation of the input member136 a relative to the output member 136 b, such as would be desiredduring a leg swing phase of a gait cycle of the robotic device). In thismanner, the quasi-passive elastic actuator 134 is switchable between theelastic state and the inelastic state, such that the quasi-passiveelastic actuator 134 applies an augmented toque (in the elastic state)in parallel with a torque applied by the primary actuator 134. Thiscombined torque functions to rotate the output member 136 b relative tothe input member 136 a in a more efficient manner as less torque isrequired by the primary actuator to perform the specific gait phase,thereby reducing the power requirements/demands of the primary actuator134, as further detailed below.

In one example, the quasi-passive elastic actuator 134 can bestructurally mounted to the primary actuator 132 by a first mountingplate 138 a and a second mounting plate 138 b, each positioned on eitherside so as to constrain the primary and secondary actuators 132 and 134in a “sandwich” state (see FIGS. 7A-8B). The first mounting plate 138 ais mounted to a housing mount 140 of the primary actuator 132 via aplurality of fasteners 142 (with spacers there between). The firstmounting plate 138 a comprises a primary aperture 144 a (FIG. 8B) thatrotatably supports a collar bearing 146 of the primary actuator 132, andcomprises a secondary aperture 144 b that rotatably receives a collarbearing 148 (FIG. 8B) supported by the quasi-passive elastic actuator134.

The second mounting plate 138 b is mounted to the other side of thehousing mount 140 via a plurality of fasteners 151, and comprises aninput aperture 152 that rotatably supports a collar bearing 154 (FIG.8A) coupled to the quasi-passive elastic actuator 134. Therefore,collectively the input aperture 152 of the second mounting plate 138 band the secondary aperture 144 b of the first mounting plate 138 a aresized to structurally support the quasi-passive elastic actuator 134 andto facilitate rotation of the quasi-passive elastic actuator 134 via thecollar bearings 148 and 154 supporting either side of the quasi-passiveelastic actuator 134.

The input member 136 a can be a load transfer component that cancomprise many different shapes and forms, depending upon the particularapplication (e.g., exoskeleton, humanoid robot, robotic hand or arm),and depending on the support member attached to the input member 136 a(e.g., such as support member 105 b of FIG. 4A). As such, the specificconfigurations shown are not intended to be limiting in any way. In thepresent example, the input member 136 a can comprise a horizontal flange156 and a rotary interface aperture 158 (FIGS. 7A and 8A). Thehorizontal flange 156 can be received and seated against a horizontalstep portion 160 of the second mounting plate 138 b to restrict movementof the input member 136 a relative to the second mounting plate 138 b,and thereby relative to the housing mount 140 of the primary actuator134. The rotary interface aperture 158 can be coupled to an inputinterface member 162 of a first vane device 164 (see FIGS. 10A and 10B)that extends through the input aperture 152 of the second mounting plate138 b. The input member 136 a can comprise a robotic support memberinterface portion 166 coupleable to a support structure of a roboticassembly, such as the support member 105 b of FIG. 4A.

The output member 136 b can be a load transfer component that cancomprise many different shapes and forms, depending upon the particularapplication (e.g., exoskeleton, humanoid robot, robotic hand or arm). Assuch, the specific configurations shown are not intended to be limitingin any way. In the present example, the output member 136 b can comprisean actuator interface portion 168 secured to a housing 170 of thequasi-passive elastic actuator 134 via fasteners (not shown).Alternatively, the output member 136 b can be formed as an integral partof the housing, and be disposed closer to the axis of rotation 137, suchas described below regarding FIGS. 12A-12E, and shown in the exampleexoskeleton of FIGS. 4A-5B.

The output member 136 b can comprise a robotic support member interfaceportion 172 coupleable to a support structure of a robotic assembly,such as the exoskeleton of FIG. 4A. Therefore, as the quasi-passiveelastic actuator 134 rotates about the axis of rotation 137, the outputmember 136 b (and its associated support member) concurrently rotateswith the attached housing 170 about the same axis of rotation 137.

With regards to the primary actuator 132 (see particularly FIGS. 9A and9B with the primary actuator 132 shown in an exploded view), cancomprise a housing mount 140. The housing mount 140 comprises a firstmount structure 174 a and a second mount structure 174 b coupled to eachother via fasteners 176. The first and second mount structures 174 a and174 b are fastened together to house and structurally support many ofthe components of the primary actuator 132. For instance, the primaryactuator 132 comprises a motor 178 that is seated in respective annularrecesses of the first and second mount structures 174 a and 174 b. Themotor 178 can be a high-performance Permanent Magnet Brushless DC motor(PM-BLDC), which can be a variant of a frameless torque motor withwinding optimized to achieve the desired maximum torque and speed whileoperating using a 48 VDC supply and a high-performance COTS controller,such as motor MF0127-032 marketed by Allied Motion. Controlling abrushless electric motor is well known and will not be discussed indetail, but it will be appreciated that any number of control schemescan be used in combination with the motor and sensors associated withthe tunable actuator joint module 130 to operate the motor. The motordescribed above and shown in the drawings is not intended to be limitingin any way. Indeed, other motors suitable for use within the primaryactuator 132 are contemplated herein, as are various other types ofactuators, such as hydraulic actuators.

The motor 178 can comprise a stator 180 and rotor 182 rotatable relativeto each other (in a typical fashion for commercially available framelessbrushless motors). The motor 178 can be configured to comprise a centralvoid 184 about the central area of the motor 178 and surrounded by therotor 182. Advantageously, a transmission, such as the planetarytransmission 186, can be positioned and supported within (entirely orpartially) the central void 184. This provides a low-profile gearedmotor state with high torque output for a relatively small electricmotor, as exemplified below. It should be appreciated that the planetarytransmissions exemplified herein can be replaced (or supplemented with)other transmission types, such as harmonic, cycloidal, worm, belt/chain,crank, four-bar linkage, backhoe linkage, bell crank, continuouslyvariable, or any others as will be recognized by those skilled in theart. These other types of transmissions are not detailed herein as thoseskilled in the art will recognize how these may be implemented withoutundue experimentation.

Planetary transmissions are well known and will not be discussed ingreat detail. However, in the present example the planetary transmission186 can be configured as a 4:1 geared planetary transmission. Thus, inone example the planetary transmission 186 can comprise an outer ring190 engaged to four planet gears 188 (one labeled) mounted about acarrier 192, whereby the four planet gears 188 have gear teeth thatengage with the gear teeth of a central sun gear 194 (FIG. 9B). Withplanetary transmissions generally, the stationary component can be anyone of the outer ring 190, or the carrier 192, or the sun gear 194, forinstance, whereby the other two components are rotatable relative to thechosen stationary component.

In the present example, the outer ring 190 is stationary, as it isfastened to the first mount structure 174 a via fasteners (not shown)through apertures 196 around the outer ring 190 and into threaded bores197 in the first mount structure 174 a. A rotatable transfer wheel 198(FIG. 9A) is disposed on an outer side of the primary actuator 132adjacent the second mount structure 174 b, and is fastened to a drivecollar 200 via perimeter fasteners 202. The drive collar 200 is fastenedor fixed to the rotor 182 of the motor 178. The transfer wheel 198 isoperable to transfer rotation from the rotor 182 of the motor 178 to thesun gear 194 about the axis of rotation 203 (FIG. 8A). A spacer sleeve201 can be positioned adjacent the drive collar 200 and between theouter ring 190 of the planetary transmission 186 and the rotor 182 toact as a support spacer between the planetary transmission 186 and therotor 182.

The transfer wheel 198 can comprise a central aperture 204 that supportsa transfer hub 206 that is fastened to the transfer wheel 198 viafasteners 208. The transfer hub 206 can have inner gear teeth (notshown) that can be engaged with outer gear teeth of the sun gear 194.Therefore, upon applying an electric field to the motor 178, the rotor182 rotates about axis 203, which causes the transfer wheel 198 torotate, which thereby causes the sun gear 194 to rotate, all in a 1:1ratio. Upon rotation of the sun gear 194 about axis of rotation 203, theplanetary gears 188 rotate around the sun gear 194, which causes thecarrier 192 to rotate. An output shaft 209 is secured to a centralportion 211 of the carrier 192, such that rotation of the carrier 192causes rotation of the output shaft 209 about axis 203, which provides a4:1 geared-down transmission arrangement from rotation of the rotor 182to the output shaft 209 via the planetary transmission 186. Otherplanetary transmission types and gear reduction schemes can be usedinstead of a 4:1 transmission, such as a 3:1 or a 2:1 (or even greaterratios) planetary gear scheme.

To reduce build height, the planetary transmission 186 can be positionedinside of the rotor 182 of the motor 178. Depending on the motorselected, the inside diameter of the rotor will dictate the maximumoutside diameter of the planetary transmission. Once the planetary ringhas been constrained by its outside diameter, there are a limited amountof options for gear ratios and output torques available. The outputratio is determined from the ratio of the number of teeth on the ringgear to the number of teeth on the sun gear. To obtain a higherreduction in the compact design of the planetary unit, the sun geardiameter can be reduced, which generally corresponds to less powertransmission. The capacity to transmit higher torques is reduced with asmaller sun gear. A balance of reduction and strength can be determinedfor a planetary unit that will physically fit inside the motor rotor. Byimplementing a helical cut gear, higher forces can be transmitted on thegear teeth making the unit stronger. A wider tooth will also improve theload carrying capacity of the sun gear, however this increases theweight as well.

In addition, the sun gear 194 makes contact with several teethsimultaneously so the contact ratio is much higher than a conventionalspur gear transmission. Another benefit of planetary gears is the factthat the transmission is in-line with the motor, which allows forcompact mounting states. Two of the 4:1 planetary units (one shown onFIG. 9B) can be nested together to produce a 16:1 final drive, forinstance.

Thus, in one example using Allied Motion's MF0127-032 motor, it has aninside diameter of 3.3 inches, which means that a planetary transmissionof approximately 3.15 inches (or less) could be used and disposed in thecentral void of the motor. And, Matex's 75-4MLG12 planetary transmissioncan be incorporated, which is a 4:1 unit with a 2.95 inch outsidediameter having a 118 N-m peak torque, weighing just 500 grams. Suchplanetary transmission could be incorporated with a brushless motor asdiscussed herein to generate a compact configuration. Therefore, in theillustrated example of FIG. 9B, the output shaft 209 applies arelatively higher torque at a low speed with very little noise andbacklash via the planetary transmission 186, all in a compact formbecause the planetary transmission 186 is housed within the void 184 ofthe brushless frameless electric motor 178, for instance. It is notedthat the specific types of motors and planetary transmissions describedherein are not intended to be limiting in any way, as will be recognizedby those skilled in the art.

With continued reference to FIGS. 9A and 9B, a free end 210 of theoutput shaft 192 extends through an aperture 212 of the first mountstructure 174 a. A tapered support collar 214 surrounds and is coupledto the output shaft 192 (a key and slot interface can be used to couplethe support collar 214 to the output shaft 192). The tapered supportcollar 214 has an outer tapered surface that mates to an inner taperedsurface of a primary pulley 216 (e.g., such as a Morse taper interface)to couple the output shaft 192 to the primary pulley 216 (a key and slotinterface can be used to couple the support collar 214 to the primarypulley 216). A first collar bearing 218 a is positioned within theaperture 212 (FIG. 9A) of the first mount structure 174 a to rotatablysupport the output shaft 192, and a second collar bearing 218 b ispositioned with an outer end of the primary pulley 216 to rotatablysupport the free end 210 of the output shaft 192.

In one example, a sensor plate 220 can be fastened to an outer side ofthe second mount structure 174 b, and has an aperture that supports aposition sensor 222. The position sensor 222 is adjacent the transferwheel 198, which has an aperture through to the sun gear 194 to allowthe position sensor 222 to determine the position of the sun gear 194,which can ultimately determine the rotational position of the outputshaft 209, thereby providing the angular position of a knee or hipjoint, for instance. The position sensor 222 can be any suitable sensor,such as a 13-bit hall-effect sensor. Additional positions sensors can becoupled to the system, and utilized to ultimately determine the positionof the joint. As discussed above regarding the graphs of FIGS. 3B and 3C(and below regarding the valve assembly), the particular position of theknee joint is relevant in determining and controlling actuation of avalve assembly to switch the tunable actuator joint module between theinelastic and elastic or semi-elastic states (e.g., engage and disengagethe elastic actuator), or to dynamically vary a zero point or positionof the elastic actuator, as further discussed below.

Referring back to FIGS. 6A-8B, upon rotation of the output shaft 209 (ineither rotational direction) by operating the motor 178, the primarypulley 216 rotates a transmission belt 224 that is coupled to thequasi-passive joint actuator 134 (as further discussed below) to providea primary torque to rotate the tunable actuator joint module 130 torotate the knee joint, for instance. The transmission belt 224 can be aGates Poly Chain GT Carbon synchronous belt, or other suitable belt. Abelt tensioning device 225 (FIGS. 7B and 8B) can be adjustably slidablycoupled to a slot of the first mounting plate 138 a via a fastener,which is operable by a user with a tool to slide the belt tensioningdevice 225 toward or away from the belt 224 to tighten or loosen thebelt 224, as desired. In some examples, various othertorque-transmitting devices can replace the particular configuration ofthe belt 224, such as one or more belts or linkages or gears or tendonsor others (or combinations of such). The torque-transfer device can bearranged to have an axis of rotation that is offset (e.g., oriented in adirection along a plane that is perpendicular or orthogonal or someother angle) to the axis of rotation 203 of the primary actuator 132 (orsome other angle other than parallel). And, various transmissions can bearranged to provide different gear reductions from input to output,including a relatively high gear reduction (e.g., 20:1, or more), or arelatively low gear reduction (e.g., 1:1), or any gear reduction betweenthese, depending on the particular application. In some examples, thetorque-transmitting device in the form of belt 224, or such variousalternative torque-transmitting devices, can allow the primary actuator132 to be remotely located away from the output (i.e., the primaryactuator 132 is located a given distance away from the output of thetunable actuator joint module, but operably connected thereto via thetorque-transmitting device), wherein the remotely located primaryactuator 132 can be actuated and its torque transferred to the output ofthe tunable actuatable joint module corresponding to a joint of therobotic system. For instance, the primary actuator 132 could be locatedat a lower back area of an exoskeleton (e.g., FIG. 4A), while suchalternative torque-transmitting device(s) could transfer the primarytoque from the lower back area to an output member located in thetunable actuator joint module for the hip joint for actuating the hipjoint.

With regards to the quasi-passive elastic actuator 134 (particularlywith reference to FIGS. 10A and 11B), the quasi-passive elastic actuator134 is operable to apply an augmented or supplemental torque (e.g., tothe output member 136 b, which can be fixed to a support member, such asa robotic support member). The input member 136 a and the output member136 b can each be rotatable about the axis of rotation 137 (or rotatableabout different axes). Notably, the axis of rotation 137 issubstantially parallel to the axis of rotation 203 of the primaryactuator 132 (see FIG. 7A). This contributes to the compact nature ofthe tunable actuator joint module 130 because the primary actuator 132and the quasi-passive elastic actuator 134 are vertically positioned, orstacked, relative to one another (e.g., see FIGS. 6A-6D), which locatessubstantially all of the mass of the tunable actuator joint module 130proximate or near the axis of rotation 137 of the joint (i.e., about theinput and output members 136 a and 136 b).

In one example, the quasi-passive elastic actuator 134 can comprise arotary pneumatic (e.g., or other) actuator having a rotary pneumaticspring as the elastic component that is selectively operable (e.g.,engageable and disengageable at select times and for select durations)to apply an augmented torque to the output member 136 b along with thetorque applied by the primary actuator 132, or to generate and apply abraking force. The quasi-passive elastic actuator 134 can be madeselectively operable via control of a valve assembly associated with theelastic actuator 134 (discussed further below). The quasi-passiveelastic actuator 134 is operable to selectively store energy (elasticstate) upon a first rotation of the input member 136 a, and toselectively release energy (elastic state) upon a second rotation of theinput member 136 a to apply an augmented torque to the output member 136b in parallel with the torque applied to the output member 136 b by theprimary actuator 132, where the release of the energy and the augmentedtorque are caused to occur at phases, or portions of phases, of the gaitcycle that exhibit an elastic response (see FIG. 3A). The quasi-passiveelastic actuator 134 is further configured, upon a third rotation, toneither store nor release energy (inelastic state) about thequasi-passive elastic actuator 134. Likewise, a braking force can begenerated during certain operating scenarios where it may be desirableto brake or restrict, to some degree, rotation of the joint. The brakingforce can be applied to restrict rotation when the primary actuator isinactive, but rotation of the input member and joint are still occurring(e.g., in response to an external force), but this is not intending tobe limiting as the braking force can be applied at a time when theprimary torque is being applied to the output member from the primaryactuator.

The housing 170 of the quasi-passive elastic actuator 134 can comprise ahousing body 226 and a faceplate 228 fastened together via a pluralityof fasteners 230, and that collectively define a cavity 232 (FIG. 10B)of the housing 170. A first vane or vane device 164 and a second vane orvane device 229 are supported by the housing 170 and rotatable relativeto each other about the cavity 232. The input interface member 162 ofthe first vane device 164 extends through a central aperture 234 of thefaceplate 228 (and through the input aperture 152 of the second mountingplate 138 b (see FIG. 7A)).

The input interface member 162 is rotatably supported about thefaceplate 228 by a collar bearing 236. The collar bearing 236 is held inposition by a ring 241 fastened to the faceplate 228. The inputinterface member 162 comprises key slots 238 disposed radially aroundthe input interface member 162, and that receive keys/rods (not shown)that interface with corresponding key slots formed internally about acentral aperture 240 of the input member 136 a.

Opposite the input interface member 162 of the first vane device 164 isa cylindrical stabilizing portion 242 (FIG. 10A) that extends through acentral aperture 244 of the chamber body 226, and is rotatably supportedto the housing 170 by a collar bearing 246 that surrounds the annularstabilizing portion 242. The collar bearing 246 can be seated in anouter recess of the housing body 226. A ring 248 can be fastened to thehousing body 226 to retain the collar bearing 246 about the housing body226. The collar bearing 148 surrounds an outer annular member 250 of thehousing body 226 and is rotatably interfaced with the secondary aperture144 b of the first mounting plate 138 a (see FIG. 7B) to rotatablysupport the housing body 226 with the mounting plate 138 a.

With continued reference to FIGS. 10A and 10B, and with reference toFIGS. 14A-14B, the first vane device 164 can be a unitary or uniformbody that comprises a cylindrical body portion 252 and an elongated vane254 extending from the cylindrical body portion 252. In one example, thesecond vane device 229 can comprise an elongated vane positioned suchthat it extends approximately 180 degrees from the elongated vane 254 ofthe first vane device 164 when in a nominal position (FIG. 11A). Thesecond vane device 229 can be fixed to the housing body 226 and thefaceplate 228 by a pair of pins 258 (FIG. 10B) that extend laterallythrough either end of the second vane device 229. The pair of pins 258extend into receiving bores of the housing body 226 and the faceplate228. Thus, the second vane device 229 is fixed to the housing 170, suchthat rotation of the housing 170 about the axis of rotation 137 causesconcurrent rotation of the second vane device 229 relative to the firstvane device 164 (see e.g., comparison and discussion of FIGS. 11A and11B). In this manner, the second vane device 229 has an interfacesurface 260 that slidably engages the outer surface 262 of thecylindrical body portion 252 of the first vane device 164 (FIG. 14A).

As can be appreciated from FIGS. 11A and 11B, the first vane device 164and the second vane device 229 define a compression chamber 264 a and anexpansion chamber 264 b (as also defined by the boundaries of the cavity232 of the housing 170). The location of the second vane device 229relative to the first vane device 164 can define the volume of thesechambers. In one example, the second vane device 229 can be located 180degrees from a 0 degree position of the first vane device 164, whereinthe compression and expansion chambers 264 a and 264 b, respectively,comprise the same volume, as shown on FIG. 11A. Note that the crosssectional view of FIG. 11A is inverted relative to the position shown onFIG. 10B. The second vane device 229 can be located relative to thefirst vane device 164 at other positions so as to provide or definecompression and expansion chambers having disparate volumes, or in otherwords different volume ratios, when the quasi-passive elastic actuatoris in the inelastic state or mode (that facilitating free-swing).Furthermore, the elastic component can be pre-charged prior to the firstrotation, such that a pressure differential exists between thecompression chamber and the expansion chamber.

The cavity 232 (i.e., the compression and expansion chambers 264 a and264 b, respectively) of the housing 170 can be gas pressure charged to anominal pressure (e.g., approximately 1500 psi) via a valve 269 (FIG.10B), such that both chambers 264 a and 264 b have equalized gaspressure when the first vane device 164 is at its nominal position (theposition of the rotor vane relative to the second vane device when thequasi-passive elastic actuator is in the inelastic mode just prior toentering the elastic mode) (e.g., 180 degrees relative to the secondvane device 229, 90/270 degrees relative to the second vane device 229,and others) (and when the valve assembly is open, as discussed below). Acompression chamber valve 267 a and an expansion chamber valve 267 b(FIG. 10B) are each in fluid communication with respective compressionand expansion chambers 264 a and 264 b to facilitate removing or addingan amount of gas pressure in each or both chambers as desired togenerate a particular spring stiffness value. In some example, thisspring stiffness value can be dynamically modified by the operator whilein the field of use. For instance, a person or operator wearing anexoskeleton may desire a stiffer knee joint when performing a particulartask or carrying a certain load. Accordingly, the nominal gas pressurein the cavity 232 can be dynamically tuned or modified in real-time andin the field by removing or adding gas pressure within the housing 170via the valves, thus permitting a variable joint stiffness value withinthe quasi-passive elastic actuator. This is an advantage over systemsthat have a manufactured spring stiffness that is not modifiable by auser. In any event, the quasi-passive elastic actuator can bepre-charged with a pre-charge pressure to comprise a predetermined jointstiffness value. In some examples, “pre-charge” refers to injecting orintroducing pressurized gas (i.e., above ambient) into both thecompression and expansion chambers 264 a and 264 when the first andsecond vane devices are at their nominal positions (e.g., 180 degreesrelative to each other, in the above example). Therefore, the higher thepre-charge pressure (e.g., 200 psi vs. 1646 psi), then the greater thespring stiffness value for a particular actuator joint module, because agreater gas pressure would result in a particular compression chamberwhen pre-charging with a higher gas pressure with the same amount ofrotation of the first vane device relative to the second vane device,when comparing the resulting compression chamber pressure of differingpre-charge gas pressure values. This is one example of what is meant bythe term “tunable” actuator joint module, because the example actuatorjoint modules discussed herein can be tuned to have a particular jointstiffness value by selecting the amount of gas pressure charged in (orremoved from) the chambers of the actuator joint modules, as will beappreciated by the examples and discussion herein.

Upon rotation of the input member 136 a relative to the output member136 b about the axis of rotation 137 (e.g., in the counter clockwisedirection of FIG. 11B), the quasi-passive elastic actuator can beengaged so as to cause the first vane device 164 to rotate (e.g., thefirst vane device 164 can be caused to rotate approximately 90 degrees,for instance (in practice, the rotation may be more or less than 90degrees)). Such rotational movement can be the result of a gaitmovement, external forces, or other type of movement, that causes afirst support member to rotate about a second support member, such asbetween the points A to B of FIG. 3A. That is, the input and outputmembers 136 a and 136 b would rotate relative to each other, as beingsecured to respective first and second support members of a roboticassembly, for instance (e.g., FIG. 4A). Accordingly, upon such rotation,gas (e.g., air, nitrogen, carbon dioxide, argon, Freon, a mixture ofgases, etc.) within the compression chamber 264 a can be compressedbetween the first vane device 164 and the second vane device 229,thereby storing energy therein, as illustrated in FIG. 11B (thecompressed gas exhibiting spring-like behavior). And, upon a second gaitmovement, such as between points B to C of FIG. 3A, the input member 136a is initiated to rotate relative to the output member 136 b in theopposite direction (i.e., clockwise direction) (again, rotating in theopposite direction is not required as energy can be stored and releasedduring rotation in the same direction in other examples). Accordingly,with the elastic actuator engaged (either still engaged, or engagedselectively at a later time), compressed gas in the compression chamber264 a expands, thereby releasing stored/potential energy harvestedduring the first rotation or gait movement. This expanding gas pushes orcauses a biasing force to the elongated vane 254 of the first vanedevice 164. As a result, a torque is exerted by the first vane device164 relative to the second vane device 229 to rotate the second vanedevice 229 and the attached housing 170, which consequently applies theaugmented torque to the output member 136 b. Notably, during rotation ofa particular joint module, the spring stiffness of the joint module isvaried because of the nonlinear manner (with the valve assembly in thefully closed position) in which energy is stored when continuallycompressing gas in a compression chamber. Thus, the spring stiffnesswill vary through the various degrees of compression and expansioncycles as the quasi-passive elastic actuator is actuated during variousdegrees of rotation of the joint module and corresponding joint.

In some examples, the manufactured position of the second vane device229 can be selected at a certain position to achieve a desired elasticresponse. For instance, the second vane device 229 can be fixed to thehousing 170 at less than or greater than 180 degrees relative to theelongated vane 254 of the first vane device 164, thus increasing ordecreasing the disparity between the expansion and compression volumes,or in other words, providing different and unequal compression andexpansion chamber volumes. This can be advantageous for users havingdiffering knee heights and differing gait types, or for task-specificmovements, such as crouching and jumping where knee joint rotation maybe greater than merely walking or running. Moreover, locating the secondvane device 229 at different positions relative to the first vane device164 when the valve assembly is closed can produce linear or nonlinearresponses or output. With disparate compression and expansion chambervolumes, the differential pressure can evolve more rapidly, particularlywhen the expansion chamber volume is relatively small, since the volumeratio is higher than the compression side for the same rotor rotation.This means that a lower charge pressure can be implemented to attain thesame pneumatic spring stiffness as would be obtained if the volumes wereequal.

For example, assume in one non-limiting example that the second vanedevice 229 is initially positioned 90 degrees relative to the first vanedevice 164 (see FIG. 11B as a reference to show such possible initialposition), and that the total volume of the housing body 226 isapproximately 137 cc. Accordingly, the compression chamber 264 a cancomprise a larger volume (e.g., approximately 108 cc) than the expansionchamber (e.g., approximately 29 cc). The pre-charge pressure of thecompression and expansion chambers 264 a and 264 b can be approximately1646 psi, thereby producing an 1854 psi peak at 20 degrees rotation,which produces 140 N-m of torque. This pre-charge pressure of 1646 psican accomplish a targeted joint stiffness of 7 N-m/deg. Positioning thesecond vane device 229 in a position other than 180 degrees apartrelative to each other provides disparate expansion and compressionchamber volumes, which maintains lower charge and actuation pressures(as compared to the “180 degree” positioning example and substantiallyequal volumes) because the first vane device 164 requires about half therotational movement to achieve the same amount of energy storage aboutthe compression chamber 264 a as compared to if the volumes were equal.This can also reduce or minimize the size and weight of a particularquasi-passive elastic actuator because a smaller chamber volume ispossible. This is another example of what is meant by the term “tunable”actuator joint module, because the example actuator joint modulesdiscussed herein can be tuned to have a particular joint stiffness valueby selecting the initial or starting position of the second vane device229 relative to the first vane device 164, as will be appreciated by theexamples and discussion herein.

In one example, as shown in FIGS. 14A and 14B (and with continuedreference to FIGS. 4A-11B), a pair of small ring seals 259 can each bedisposed on either side of the first vane device 164 to seal gas fromtransferring between (or exiting) the compression and expansion chambers264 a and 264 b, respectively. Likewise, another pair of larger ringseals 261 can each be disposed on either side of the cylindrical bodyportion 252 to seal gas from transferring between the chambers 264 a and264 b, thereby providing two stages of sealing. The elongated vane 254can have a seal member 263 positioned through a slot extending through acentral area of the vane 254 to seal gas from transferring betweenchambers 264 a and 264 b. Likewise, the second vane device 229 can alsocomprise a seal member 265 disposed in a groove around the perimeter ofthe second vane device 229 to seal areas of contact around the secondvane device 229 on all four vertical/lateral sides.

As discussed above, the primary actuator 134 can be operated to apply aprimary torque (along with the augmented torque) to rotate the outputmember 136 b about axis of rotation 137. In this manner, a splined ringgear 268 can be coupled to the housing body 226 via keys 270 (FIG. 10A)that mate the splined ring gear 266 about an annular interface portion272 of the housing body 226. The splined ring gear 266 can be rotatablycoupled with the primary pulley 216 (of the primary actuator 134) viathe transmission belt 224. Therefore, upon the desired or selectedsecond gait movement, the quasi-passive actuator 134 applies theaugmented torque concurrently with the torque of the primary actuator134 to actuate the tunable actuator joint module 130 about the axis ofrotation 137. Because the torque applied by the primary actuator 132 issupplemented with the augmented torque applied by the quasi-passiveelastic actuator 134, the motor 178 can be selected from a group ofsmaller motors (e.g., having less power dissipation) than wouldotherwise be needed within a joint module not having an elastic actuatorfor accomplishing the same task or function of the robotic assembly,which further contributes to the compact configuration of the module130.

For instance, the motor 178 can be a Brushless DC motor (BLDC), such asa Permanent Magnet BLDC sold by Allied Motion (MF0127-032) having a 95mm outside diameter and a 32 mm think frameless motor with torque in therange of 40 to 60 N-m, and peak torque as large as 90 N-m, and withwinding optimized to achieve the desired maximum torque and speed whileoperating using a 48 VDC supply and a high performance COTS controller.The motor coils can be rated for operation up to 130 deg. C., so themotor may be able to operate continuously while running even at ambienttemperature as high as 50 to 60 deg. C. (122 to 140 deg. F.), butideally at a steady state temperature of approximately 40 degrees C.above ambient. Of course, this is only one specific example that is notintended to be limiting in any way.

In one example of power usage, assume a lower body exoskeleton (e.g.,FIG. 4A) includes left and right hip joints for flexion/extension, andknee joints for flexion/extension, where each of these joints comprisesa tunable actuator joint module as discussed herein. While walking atapproximately 3.5 mph, the total power usage to actuate each hip jointis approximately 90 W per gait cycle, while operating at approximately40 degrees C. above ambient. And, the total power usage to actuate eachknee joint is approximately 70 W per gait cycle, while operating atapproximately 60 degrees C. above ambient. Thus, the total average powerfor two exoskeleton legs (while walking) is approximately 320 W (i.e.,90+90+70+70). Therefore, the energy used per meter while walking isapproximately 213 J/m (or a travel distance of approximately 17 km/kW-hrused).

While running at approximately 6 mph, the total power usage to actuateeach hip joint is approximately 150 W per gait cycle, while operating atapproximately 70 degrees C. above ambient. And, the total power usage toactuate each knee joint is approximately 145 W per gait cycle, whileoperating at approximately 60 degrees C. above ambient Thus, the totalaverage power for two exoskeleton legs (while running) is approximately590 W.

These same two example operating conditions (walking and running) can beachieved with a tunable actuator joint module weighing approximately5.08 kg (or less depending on material choices and other variables), andhaving a max torque of 300 N-m for the primary actuator (e.g., motor andone planetary transmission). The maximum torque for the quasi-passiveelastic actuator (i.e., that which applies an augmented torque) can be460 N-m for a hip joint (with a 645 psi pre-charge), and 350 N-m for aknee joint (with a 1525 psi pre-charge). These results are with amaximum speed of 600 degrees/second for each hip and/or knee joint. Insome examples, the pre-charge pressure can be up to 3000 psi, with aburst pressure of 5000 psi or less. Note that the ankle joints can havethe performance results discussed below regarding the linear pneumaticactuator of FIGS. 20A-20F.

In some examples, a second transmission, such as a second planetarytransmission, can be incorporated with the primary actuator 132 toprovide further gear reduction. For instance, a low or high drive secondplanetary transmission could be coupled to the output (e.g., carrier) ofthe planetary transmission 186, and the output of the second planetarytransmission could be coupled to the output shaft 210. Thus, suchcascaded planetary transmissions and the transmission belt 224 canprovide a three stage gear reduction from the original output torque andspeed of the motor 178.

In the example illustrated in FIGS. 6A-10B, the planetary transmission186 can be a 4:1 transmission with the belt 224 providing a 2.05:1transmission reduction (as a result of the larger diameter of the gearring 268 and the smaller diameter of the output pulley 216, as discussedabove). The resulting ratio gear reduction from the motor 178 to theoutput member 136 b can be 8.2. In an example where the motor 178 is a48V motor (and Allied Motion's motor mentioned above), the maximumoutput torque can be approximately 342 N-m, and the maximum output speedcan be 1008 degrees/second. This example is not meant to be limiting inany way. In another example, the belt 224 can provide a 1:1 transmissionreduction, or it can vary from this ratio. Likewise, the planetarytransmission can be a 3:1 or a 5:1 (or even greater ratios), asmentioned above. As will be recognized by those skilled in the art, andsimilar to the first transmission discussed above, other types oftransmission types can be incorporated and used as a secondtransmission. In some examples, other frameless, brushless motors (orother types of primary actuator types (e.g., hydraulic, pneumatic)) canbe incorporated, as discussed above, to generate a maximum output torquethat is greater or less than 342 N-m, and greater or less than a maximumoutput speed of 1008 degrees/second, depending on the particularrequirements of the joint to be actuated.

FIGS. 12A-12F show various views of the tunable actuator joint module109 a, as exemplified in FIGS. 4A-5B as an actuator for a knee joint ofa robotic assembly. The support member 150 b (FIGS. 4A and 5A) canstructurally support the tunable actuator joint module 109 a by beingfastened or otherwise secured or coupled to the tunable actuator jointmodule 109 a, such as to mounting plates 338 a or 338 b or both. Thesupport member 150 b can comprise an opening 301 that receives andsupports other structural support members, such as an exoskeleton asshown in FIGS. 4A and 5A. The tunable actuator joint module 109 a canhave substantially all the same components and functionality asdescribed above regarding the tunable actuator joint module 130, exceptthat the output member 336 b of the quasi-passive elastic actuator 134is formed as part of the housing 370, as best shown in FIG. 12E. Eitherway, the input member 336 a and the output member 336 b rotate aboutaxis 107 c, as in FIGS. 4A and 12A.

It should be appreciated that many of the components and functionalityof the tunable actuator joint module 130 described above regarding FIGS.6A-11B can be readily incorporated with the tunable actuator jointmodule 109 a of FIGS. 12A-12F. To this end, FIGS. 12A-12F will not bediscussed in great detail; however, the same components are labeled inFIGS. 12A-12F as corresponding to the same components of the tunableactuator joint module 130 of FIGS. 6A-11B.

Thus, the quasi-passive elastic actuator 134 and the primary actuator132 are operative to apply a torque to rotate the input member 136 arelative to the output member 336 b, which can rotate support member 105c (FIG. 4A) relative to support member 105 b, for instance. Or, thequasi-passive elastic actuator 134 can be operable to apply a brakingforce to restrict rotation of the input member 136 a relative to theoutput member 336 b. Note that the only substantive difference betweenthe example of FIGS. 12A-12F and the example of FIGS. 6A-11B is the factthat the output member 336 b is formed as part of the housing body 226of the housing 170 (as opposed to coupled to and extending from thehousing body 226, as shown with output member 136 b regarding FIGS.6A-11B). In this manner, output member 336 b can be coupled to one sideof support member 150 c (FIG. 5A), and input member 336 can be coupledto the other side of support member 150 c (FIG. 5B). Although not shownin FIGS. 12A-12F, the quasi-passive elastic actuator 134 can support afirst vane device (e.g., 164), second vane device (e.g., 229), and avalve assembly (discussed below) disposed through the first vane device,and controllable to switch the quasi-passive elastic actuator 134between inelastic and elastic states, similar to or the same as thequasi-passive elastic actuator of FIGS. 6A-11B.

Notably, the quasi-passive elastic actuator 134 can be positionedlaterally adjacent a human knee joint (while wearing the exoskeleton ofFIG. 4A), such that the axis of rotation 107 c is at or near the axis ofrotation of the human knee joint. This can minimize the moment ofinertia of one support member 105 b relative to the coupled adjacentsupport member 105 c because the axis of rotation 107 c is positioned ator near the axis rotation of the human knee joint, so less work/power isrequired as compared to exoskeleton joints that are not positioned at ornear the axis of rotation of the human knee joint. This also positionsthe mass of the tunable actuator joint module 130 near the axis ofrotation of the human knee joint, which can also assist to minimize thepower requirements of the primary actuator to actuate the joint module130 because less work/power is required to actuated the tunable actuatorjoint module 130 as compared to exoskeleton joints having a masspositioned distally away from the axis of rotation of the human kneejoint.

FIG. 13A shows another example of a quasi-passive elastic actuator 500,and FIG. 13B shows a vertical cross sectional view of the quasi-passiveelastic actuator 500 along lines 13B-13B of FIG. 13A. The quasi-passiveelastic actuator 500 is similar to and can function in a similar manneras the quasi-passive elastic actuator 134 of FIG. 6A (and thequasi-passive elastic actuator 109 a of FIG. 5A), such that it isoperable with a primary actuator (e.g., 132) to apply an augmentedtorque to actuate a tunable actuator joint module (not shown herein, butsee, for example, the tunable actuator joint modules 109 a, 130discussed above), or to apply a braking force to restrict rotation ofthe input member relative to the output member within the tunableactuator joint module, as described herein. As such, the abovediscussion can be referred to in understanding the quasi-passive elasticactuator 500. The quasi-passive elastic actuator 500 can comprise afirst housing body 502 a rotatably coupled to a second housing body 502b, and defining a cavity 503 that can be pressurized to a desired gaspressure (as described above). A first vane device 504 can be rotatablysupported on either end by each of the housing bodies 502 a and 502 b.An output member 506 can be coupled to an output end of the first vanedevice 504.

The second housing body 502 b can operate as an input member (e.g., aspart of, or coupled to, a robotic support member), and can be coupled tothe other end of the first vane device 504. A second vane device (notshown here, but similar to FIG. 10B) can be coupled to the first housingbody 502 a and can be operable with the first vane device 504, such asis described above, with respect to FIGS. 10A-11B. The output member 506can be coupled to a support member, which can be coupled to, or be partof, a robotic support member (e.g., a lower leg member). An annular ringgear 510 can be secured to the first housing body 502 a, and can becoupled to a primary actuator (e.g., 132) via a transmission belt (e.g.,belt 224).

Therefore, similarly as described above regarding the tunable actuatorjoint module 130, upon rotation of the input member in the form of thesecond housing body 502 b relative to the output member 506 about anaxis of rotation 512, the first vane device 504 can be caused to rotate.Such rotational movement can be the result of a gait movement of arobotic assembly, such as between points A and B of FIG. 3A. That is,the input and output members can rotate relative to each other, as beingsecured to respective first and second support members, for instance(e.g., see FIG. 4A). Accordingly, upon such rotation, gas within a gascompression chamber (e.g., 264 a of FIG. 11B) is compressed between thefirst vane device 504 and the second vane device (e.g., 229), therebystoring energy therein (or generating a braking force). Upon a secondgait movement, such as between points B to C of FIG. 3A, the inputmember in the form of the second housing body 502 b is initiated torotate relative to the output member 506, such as in the oppositedirection (again, rotation may be in the same or different directions).Accordingly, compressed gas in the gas compression chamber expands torelease potential energy stored therein. This expanding gas pushes orcauses a force to be exerted on an elongated vane 514 of the first vanedevice 504. As a result, a torque is exerted by the first vane device504 relative to the second vane device (e.g., 229) to rotate the firsthousing body 502 a and to apply an augmented torque to the output member506 that supplements the torque provided by the primary actuator torotate the input and output members during the second gait movement.

During such second gait movement, a primary actuator (e.g., 132) rotatesthe transmission belt, which rotates the annular ring 510 to apply aprimary torque to rotate the first housing body 502 a, which exerts atorque to rotate the output member 506. The first vane device 504 cancomprise an opening 516 that can support and receive a valve assembly toselectively control operation of the quasi-passive elastic actuator 500,as further detailed below. As such, and although not shown here, thequasi-passive elastic actuator 500 can comprise a valve assembly similarto those described herein.

With reference to FIGS. 10A-11B, and particular reference to FIGS.14A-19, discussed are various valve assemblies that can be incorporatedwith any of the quasi-passive elastic actuators discussed herein (e.g.,109 a, 134, 500). The following description of such valve assemblieswill be described with reference to each of their respective figures, aswell as FIGS. 10A-11B, which describe and illustrate the exemplarytunable actuator joint module 130 and the quasi-passive elastic actuator134, these being included in the description for the sake of simplicityand clarity, although they are intended only as one example of a jointmodule capable of implementing any one of the valve assemblies discussedbelow and shown in FIGS. 14A-19.

As taught herein, the tunable actuator joint module 130 can beswitchable between an elastic state, a semi-elastic state, and aninelastic state with the assistance of a control system operativelycoupled to the quasi-passive elastic actuator 134 for selectivelycontrolling application of the augmented torque or the braking force(e.g., during selective portions of a gait cycle, during a lifting task,during a climbing task, in response to an external load acting on therobotic system (including gravity), or during other movements by arobotic device or system). The control system can comprise any one ofthe valve assemblies discussed herein, a first vane device (e.g., seefirst vane device 164), and a controller (not shown) for controllingoperation of a particular valve assembly. The controller can be part ofa computer system on-board the robotic system, such as onboard anexoskeleton, or remotely located, such as could be the case in ateleoperated or humanoid type of robotic system, for instance. The valveassemblies can comprise pneumatic valves operable to switch the mode ofoperation of the quasi-passive elastic actuator, such as between that ofa spring (valve closed), that which facilitates free swing of a limb(valve opened) or that of a damper or brake (valve partially opened).

Each of the valve assemblies provides or facilitates a “clutch” or“brake” type of capability that permits gas to transfer (i.e., shunt)back and forth between the compression and expansion chambers, via whatis termed a shunt circuit, when the valve assembly is opened, orpartially opened, and for gas to be restricted and compressed to providea compress the elastic component, when the valve is closed, or partiallyclosed, such as to provide controlled damping or braking when the valveis partially opened or partially closed. The shunt circuit can bedefined, at least in part, by the flow pathways of the gas between thequasi-passive actuator and one or more of its components, including thevalve assembly and one or more of its components. Different valveassemblies can comprise different flow paths, and thus differentlyconfigured shunt circuits. As such, the quasi-passive actuator cancomprise a shunt circuit that can be opened (the elastic component iscaused to enter the inelastic state), closed (the elastic actuator iscaused to enter the elastic state), or partially opened (causing theelastic actuator to enter the semi-elastic state to act as a damperand/or brake) by the selective and variable control or operation of thevalve. Spring stiffness is a function of piston (first vane device) andchamber geometries, as well as gas pressure charge. Thus, the magnitudeof stiffness for a given joint is adjustable, such as for missionspecific payloads and terrain-specific gaits while the active valvecontrols exactly when that stiffness is engaged for energy recoveryduring the support phase and when it is disengaged during the ballisticor free swinging phase. The valve assemblies discussed herein providethe tunable joint module with the ability to rapidly vary thecharacteristics of the quasi-passive actuators between that of a nearfree joint to that of a nominally linear elastic element (when opened orpartially opened). This results in power operation of the joints of therobotic system (e.g., shoulder, elbow, hip, knee and ankle joints) thatis relatively low compared with prior joints that do not have aquasi-passive elastic actuator.

The valve assemblies discussed herein can be operated and controlled tobe closed, thereby facilitating application of an augmented torque,regardless of whether the primary actuator is operated to apply aprimary torque. Thus, the term “augmented” is not meant to be limited toapplying a supplemental or additional torque with the primary torque,because the augmented torque may be the only torque applied to actuate aparticular clutched joint module. For instance, after an exoskeleton'supper body is used to lower a load (thereby storing energy aboutquasi-passive elastic actuators associated with joint modules of theupper body), and after the load is released by the upper body, the armsof the upper body may be moved upwardly and back to a normal positiononly by virtue of the “augmented torque” being applied by the associatedquasi-passive elastic actuators. This is because the primary actuatormay not be needed to move the arm back up to a normal position becausethe stored energy is sufficient for such purpose. Moreover, during suchapplication of “only” applying the augmented torque, the associatedvalve assemblies can be variably controlled to desired positions (e.g.,partially opened) to provide a damping force or braking force to controlthe speed or rate at which the respective quasi-passive elastic jointmodules move, as discussed elsewhere herein. Of course, for the samemovement, such can also be applied in addition to a primary torqueprovided by the primary actuator.

Moreover, in some examples, the valve assemblies discussed herein can belocated and operable at a joint of the robotic system. In one example,the valve assembly can be supported within an opening of the first vanedevice of the quasi-passive elastic actuator, such that the valve isintegrated into or positioned through the first vane device (andparticularly within the first vane shaft), and supported in a positionabout an axis of rotation of the tunable actuator joint module, andparticularly the quasi-passive elastic actuator. In this position, thevalve assemblies can comprise an axis of actuation that is parallel, andin some cases, collinear, with the axis of rotation of the tunable jointmodule (and a joint of the operator in some robotic systems, such aswith an exoskeleton). The axis of actuation can comprise an axis ofrotation in those cases where the valve device of the valve assembly isrotatable in a bi-directional manner to open and close the valveassembly, or an axis of translation in those cases where the valvedevice is translatable in a bi-directional manner to open and close thevalve assembly.

FIGS. 15A-15C illustrate a valve assembly 604 operable with a first vanedevice 600 (similar to the first vane device 164 described above) inaccordance with one example. In this example, the first vane device 600comprises an opening or bore 602 extending through a central area of thefirst vane device 600 and along an axis of rotation 137. The valveassembly 604 comprises a valve device 606 disposed within the opening orbore 602 of the first vane device 600. The valve device 606 can compriseat least one cylindrical portion (i.e., a portion having a cylindricallyconfigured surface) positioned through the opening 602, which interfaceswith a corresponding inner cylindrical surface of the opening 602. Ofcourse, a cylindrical cross-sectional configuration is not intended tobe limiting in any way, particularly in the example configuration inwhich the valve device 606 translates relative to the first vane device600. In one example, the valve device 606 can be situated about the axisof rotation 137, or at least have a portion that intersects the axis ofrotation 137.

The first vane device 600 can define, at least in part, a valve body ofthe valve assembly 604. In this manner, the first vane device 600 cancomprise a first conduit 605 a in fluid communication with a compressionchamber 610 a (e.g., 264 a of FIG. 11A), and a second conduit 605 b influid communication with an expansion chamber 610 b (e.g., the expansionchamber 264 b of FIG. 11A), such that, in at least one operating state,gas can be caused to move between the compression chamber 610 a and theexpansion chamber 610 b through, and as controlled by, the valveassembly 604 (a portion of which assembly comprises the first vanedevice 600). These described fluid flow paths comprise and define a partof the shunt circuit that exists between the compression and expansionchambers and the valve assembly.

The valve assembly 604 can comprise a valve actuator 612, such as avoice coil or other solenoid or electric actuator, operatively coupledto the valve device 606 to facilitate selective actuation (i.e.,movement) of the valve device 606. The valve actuator 612 can actuatethe valve device 606 by rotating it or by axially moving it about orrelative to the opening or bore 602. Thus, the valve assembly 604 andthe valve device 606 comprises an open or partially open position (FIGS.15A and 15B) that permits at least some fluid flow (i.e., the shuntingof fluid) between the compression and expansion chambers 610 a and 610b. The valve device 606 further comprises a closed position (FIG. 15C)(when actuated by the actuator 612) that restricts or blocks fluid flowbetween the compression and expansion chambers 610 a and 610 b.

More specifically, the valve device 606 comprises at least one opening614 through the valve device 606 that can be selectively positionedbetween an open, partially open, and a closed position. With the valvedevice 606 in an open position or partially open position, the opening614 is aligned, at least in part, with the first and second conduits 605a and 605 b so as to facilitate fluid communication between thecompression and expansion chambers 610 a and 610 b via the respectiveconduits 605 a and 605 b (e.g., to open or partially open the shuntcircuit, where the valve assembly functions to try to equalize pressurebetween the compression and expansion chambers 610 a and 610 b), asshown in FIGS. 15A and 15B. In the inelastic state with the shuntcircuit open where gas pressure is equalized, and where there is littleto no resistance to movement of the first vane device 600 relative tothe second vane device 603 (i.e., gas is free to move between thecompression and expansion chambers through the valve assembly as thetunable joint module is rotated), the quasi-passive elastic actuator 601neither stores nor releases energy in the form of an augmented torque tothe tunable actuator joint module 130, nor does it generate a brakingforce. Rather, the quasi-passive elastic actuator is in free swing modewhere the first vane device 600 is freely rotatable relative to thesecond vane device 603, and where negligible resistance (or reducedresistance) is generated between the first vane device 600 and thesecond vane device 603 (and consequently negligible resistance from thequasi-passive actuator is transferred to the first and second supportmembers rotatably coupled about the quasi-passive elastic actuator 601).

Thus, keeping with the discussion above regarding FIGS. 11A and 11B, thevalve assembly 604 can be selectively controlled so that it ismaintained in an open position where the shunt circuit is maintained inan open position, such that no torque assistance is provided to theprimary actuator (except in cases where the valve is variably controlledin a partially open position where some residual torque exists as adamping or braking torque). In other words, the tunable actuator jointmodule 130 can function with only the primary actuator providing anyneeded torque input, or in response to an external force (e.g., animpact force, momentum or gravity that induces rotation) during a freeswing mode. For example, during a portion of a gait movement, such as isdesired between pointsD-A (FIG. 3A), the valve assembly 604 of thequasi-passive actuator can be opened (i.e., inactive) to open the shuntcircuit, and to allow free swing of a joint of a robotic joint of arobotic exoskeleton, for instance.

Conversely, as illustrated in FIG. 15C, the valve device 606 can bepositioned in the closed position, thereby closing the shunt circuit. Inthe closed position, the quasi-passive elastic actuator 601 (e.g., 109a, 134, 500) is operable in the elastic state and is active to storeenergy and to release energy to the tunable joint actuator module. Thatis, the valve device 606 is actuated (e.g., rotated or translated) bythe valve actuator 612 to a closed position, such that the opening 614formed in the body of the valve device 606 is brought out of alignmentwith the conduits 605 a and 605 b, so as to restrict fluid communicationbetween the compression and expansion chambers 610 a and 610 b via therespective conduits 605 a and 605 b, thereby closing the shunt circuit.Thus, in this closed position, the quasi-passive elastic actuator 301functions to store energy in the form of compressed gas pressure, andthen to release the stored energy when needed in the form of anaugmented torque that supplements the torque provided by the primaryactuator to the tunable actuator joint module. As explained aboveregarding the discussion pertaining to FIGS. 11A and 11B, during a firstportion of a gait movement or gait cycle, the valve device 606 can beclosed so as to cause the quasi-passive actuator to store energy as theprimary actuator inputs a torque to cause the tunable actuator jointmodule to rotate to carry out the first portion of the gait cycle.During this rotation, the rotator vane device is displaced as discussedabove. Upon completion of the first portion of the gait cycle, a secondportion of the gait cycle, where rotation of the tunable actuator jointmodule is in the opposite direction, can take advantage of the storedenergy in the form of an augmented torque that is applied in the samedirection as the torque input by the primary actuator, the augmentedtorque generated as the compressed gas attempts to place the first vanedevice and the second vane device in equilibrium. Indeed, both thestoring and release of energy occurs with the valve assembly 604 in theclosed position of FIG. 15C to engage or actuate the quasi-passiveactuator. Although not shown, the valve device 606 of the assembly 604can be placed in a position so as to partially open the shunt circuit,wherein rotation of the joint causes the quasi-passive elastic actuator301 to be partially actuated to store (and in some cases to alsorelease) some energy that can be applied to the joint as a brakingforce.

It is further noted that the valve device 606 can be, in some examples,strategically positioned about an axis of rotation 137 of the tunableactuator joint module and the robotic joint. For example, where thevalve device 606 is rotated by the valve actuator 612, the valve device606 (or at least a component of the valve device 606) has an axis ofrotation that is congruent or parallel with the axis of rotation 137 ofthe robotic joint. Likewise, in examples where the valve device 606 isaxially translated through the opening 602, the valve device 606comprises an axis (such as an axis of translation) parallel or collinearwith the axis of rotation 137 of a robotic joint (and in some cases withthe joint of an operator, such as an operator operating an exoskeleton).

As discussed, in some examples, the valve assembly 604 and valve device606 can be controlled to actively dampen rotation of a particulartunable actuator joint module. More specifically, the valve device 606can be variably controlled to multiple different positions, between theopened and closed positions, that place the joint module, andparticularly the quasi-passive elastic actuator, in a semi-elasticstate, so that the compression and expansion chambers are in fluidcommunication with each other to some degree (e.g., the valve devicebeing 10 percent, 20 percent, 50 percent, 75 percent “open”). Inexamples, this semi-elastic state or “damping state” of thequasi-passive elastic actuator can provide a corresponding activebraking or damping force to selectively store and recover some degree ofenergy as desired. In the example shown, a controlled signal can betransmitted to the actuator 612 to variably control the rotationalposition of the valve device 606. For example, during the free swingphase the valve device 606 can be moved to a position such that theopening 614 is not completely in the open position as shown in FIG. 15B;rather, it may be rotated slightly to be partially open so that somefluid flows through the opening 614, thereby at least partiallyactuating the quasi-passive elastic actuator to provide a controlleddamping feature or damping mode to restrict or damp absolute freemovement of a particular joint module. This “active damping” can also beadvantageous in task-specific movement of the robotic system, such aswhen lowering a load. For example, with a load being carried by an upperexoskeleton, the valve devices of the elbow and/or shoulder tunableactuator joint modules can be actively and variably controlled to aposition that provides damping to control (i.e., slow down) the downwardmovement of the arm supporting the load. It will be appreciated that theposition of the various valve device examples discussed herein can alsobe variably controlled between the open and closed positions in thismanner to provide a controlled damping or braking force or component.

It should be noted that valve assembly (and the shunt circuit) can bealso be partially opened during the release of energy from thequasi-passive actuator in order to smoothen an output response. In otherwords, with the joint module configured to release energy stored by thequasi-passive actuator, the valve assembly can be partially opened andthe quasi-passive actuator placed in the semi-elastic state or dampingmode during the release of such energy, such that the output responsecan be made less nonlinear, and in some cases made linear, than wouldotherwise be the case if the valve assembly were to be fully closed. Thedegree to which the valve assembly (and the shunt circuit) can be openedand the timing of this is controllable in real-time during any rotationof the joint module.

FIGS. 16A-17E illustrate a valve assembly operable with a first vanedevice in accordance with another example. In this example, a valveassembly 654 can comprise a valve device 656. At the outset, the valvedevice 656 can comprise the same or similar features described aboveregarding valve device 606. Moreover, the valve assembly 654 is shown asbeing operable with the specific first vane device 164 described above(see FIGS. 16A and 16B).

The first vane device 164 can comprise a portion of the valve assembly654, or in other words, the first vane device 164 can form a part of orcan comprise a component of the valve assembly 654. In one example, thefirst vane device 164 can define, at least in part, a valve housingconfigured to house and facilitate operation of the valve device 656.Specifically, the first vane device can comprise a first channel 288 aformed annularly about an opening or bore 277 formed through a centralarea of the first vane device 164. The first vane device 164 includes acompression chamber conduit 290 a (see also FIGS. 14A and 14B) that canbe in fluid communication with a compression chamber as discussedherein. Similarly, a second channel 288 b is formed annularly about theopening 277 and includes an expansion chamber conduit 290 b (see alsoFIG. 14B) that can be in fluid communication with an expansion chamberas discussed herein.

The valve device 656 can be disposed and operably situated within theopening 277 of the first vane device 164, wherein the opening, and thewalls defining the opening, function as a valve housing for the valvedevice 656 (and any other corresponding components of the valveassembly). In this example, the valve device 656 comprises a movablevalve component 657 coupled to a valve actuator 662, such as by one ormore fasteners 651. The valve actuator 662 can comprise a piston 663 andan actuator device 665, such as a voice coil. The actuator device 665can be electrically coupled to a power source and a controller (notshown) to electrically control the actuator device 665 to axially movethe piston 663 along the axis of rotation 137 of the first vane device164, for instance. Therefore, the valve actuator 662 is configured toaxially move the movable valve component 657 between open, partiallyopen, and closed positions.

The valve device 656 further comprises a first valve body 659 adjacentand in support of the movable valve component 657. The first valve body659 comprises an outer annular channel 661, and a plurality of fluidopenings 664 formed through the first valve body 659 radially around theouter annular channel 661. The first valve body 659 can compriseinterface portions 668 a and 668 b on either side of the outer annularchannel 661, which can each support seals 666 that function to seal offgasses, the interface portions 668 a and 668 b and the seals 666 beingoperable to engage and interface with the inner surface defining theopening 277 of the first vane device 164.

The plurality of fluid openings 664 are each configured to be in fluidcommunication with the second channel 288 b of the first vane device 164(see FIG. 17D), which second channel 288 b is in fluid communicationwith an expansion chamber via the conduit 290 b, as discussed above. Asshown in FIG. 17A, the first valve body 659 can be generallycylindrically shaped and can comprise a central opening 672 throughwhich the movable valve component 657 translates axially, as discussedbelow.

The valve device 656 further comprises a second valve body 667 adjacentand engaged with the first valve body 659. The second valve body 667 canbe formed generally as a cylindrically shaped cap member disposed withinand interfaced with the opening 277 of the first vane device 164. At oneend, the second valve body 667 can comprise an interface portion 670that interfaces with or mates to the first valve body 659, and at theother end a cap portion 669 that seals off an inner chamber area 679defined by the various components of the valve assembly 654. The secondvalve body 667 comprises an outer annular portion 671 that has aplurality of fluid openings 673 formed radially around the outer annularportion 671. The second valve body 667 can comprise an interface portion675 adjacent the outer annular portion 671, which can help support aseal 677 to seal off gasses. The plurality of fluid openings 673 areeach in fluid communication with the first channel 288 a of the firstvane device 164 (FIG. 17D), which is in fluid communication with acompression chamber via the conduit 290 a, as discussed above.

As shown in FIGS. 17A and 17D, the valve device 656 is in the openposition, specifically showing the movable valve component 657 retractedby the piston 663, which exposes or uncovers the plurality of openings663 of the first valve body 659. Thus, the openings 664 are in fluidcommunication with the openings 673 of the second valve body 667 aboutchamber 679, which thereby places the conduits 290 a and 290 b in fluidcommunication with each other, which thereby places the compression andexpansion chambers (e.g., 264 a and 264 b, FIG. 11A) in fluidcommunication with each other, thereby equalizing pressure betweenchambers of the quasi-passive elastic actuator when in the inelasticstate, as discussed herein. Such open position can facilitate free swingmode of a robotic joint, for instance, as discussed above.

As shown in FIG. 17E, the valve device 656 is in the closed position,specifically showing the movable valve component 657 extended by thepiston 663 (upon actuation), which blocks or covers the plurality ofopenings 664 of the first valve body 659. In this position, the openings664 are not in fluid communication with the openings 673 of the secondvalve body 667, which thereby restricts fluid flow between the conduits290 a and 290 b, which thereby restricts fluid flow between thecompression and expansion chambers (e.g., 264 a and 264 b, FIG. 11A).The result is that the quasi-passive elastic actuator is placed in theelastic state to store energy or release energy, as discussed above.Although not shown, the valve device 656 can be positioned in thepartially open position to place the quasi-passive actuator in thesemi-elastic state.

Notably, the openings 664 and 673 are formed radially around theperimeters of the respective valve bodies 659 and 667. Thisconfiguration provides a radial balance of gas pressure about the firstand second valve bodies 659 and 667, and also about the movable valvecomponent 657, because an equal amount of gas pressure is passingthrough the openings 664 and 673 around the entire perimeter of thefirst and second valve bodies 659 and 667. This tends to result in equalor balanced gas pressure being exerted radially about the movable valvecomponent 657, which reduces friction when the movable valve component657 is actuated between the open and closed positions. Providing radialgas pressure balancing can reduce the amount of generated heat at agiven speed at which the movable valve component 657 is actuated. In oneexample, the movable valve component 657 can switch between the open andclosed positions in less than 15 milliseconds, or even less than 10milliseconds. This is advantageous when it is desirable to quicklyswitch the quasi-passive elastic actuator between inelastic,semi-elastic, and elastic states, such as when a user is running whilewearing an exoskeleton. This also maximizes or improves the efficiencyof the quasi-passive elastic actuator because it reduces the likelihoodthat the quasi-passive elastic actuator is engaged or disengaged at animproper time that is counterproductive to the actual movement occurringabout the joint of the robotic device.

In addition to the radial gas pressure balancing feature, the valveassembly 654 can also be axially gas pressure balanced. That is, themovable valve component 657 can comprise a cylindrically shaped tubebody that has at least one fluid opening 675 in constant fluidcommunication with a first chamber 677 (shown adjacent the piston 663;FIG. 17D) and a second chamber 679, whether in the open or closedpositions. That is, the at least one fluid opening 675 is formed throughthe movable valve component 657 adjacent the first chamber 677, which isdefined by an inner surface of the first vane device 164. And, secondchamber 679 is defined by in the inner surfaces along both of themovable valve component 657, the first valve body 659, and the secondvalve body 667. Thus, regardless of whether the valve assembly 654 is inthe closed position, partially opened position, or the opened position,there is continuous fluid communication between at least one fluidopening 675, the first chamber 677, and the second chamber 679, suchthat gas is not compressed or expanded about the first and secondchambers 677 and 679 when switching between the open, partially open andclosed positions. Thus, pressure is equalized between the first andsecond chambers 677 and 679 as the movable valve component 657 isaxially moved between the open and closed positions, which equalizationprevents gas pressure from being exerted against the movable valvecomponent 657 in either axial direction (as discussed above) duringswitching the quasi-passive elastic actuator between inelastic andelastic states. Similar in principle to the radial gas pressurebalancing discussed above, this axial gas pressure balancing tends toresult in equal axial gas pressure being exerted about the valveassembly 654, which reduces friction when the movable valve component657 is actuated between the open and closed positions, which reducesheat at a given speed at which the movable valve component 657 isactuated. This is advantageous when it is desirable to quickly switch aquasi-passive elastic actuator between inelastic and elastic states.This also maximizes or improves the efficiency of the quasi-passiveelastic actuator because it reduces the likelihood that thequasi-passive elastic actuator is engaged and disengaged at an impropertime that is counterproductive to the actual movement occurring aboutthe joint of the robotic device.

With reference to FIGS. 18A-18D, illustrated is an example valveassembly operable with a first vane device in accordance with anotherexample. In this example, a valve assembly 704 can comprise a valvedevice 706. The valve device 706 can comprise the same or similarfeatures described above regarding valve device 606, and the valvedevice 706 can be incorporated into and operable with the first vanedevice 164 described above (see FIGS. 16A and 16B).

The valve device 706 can be disposed within the opening or bore 277 ofthe first vane device 164, along the axis of rotation 137 of the roboticjoint. In this example, the valve device 706 can comprise a movablevalve component 707 coupled to a valve actuator 712, such as byfasteners 705. A first valve body 709 can be coupled to the movablevalve component 707, and the first valve body 709 can comprise a spoolhaving an opening 703 that receives and facilitates the coupling of themovable valve component 707. The spool can comprise or can be made of apolytetrafluoroethylene (PTFE) material, or other similar material.Although not meant to be limiting in any way, the movable valvecomponent 707 can be configured as a cylindrical tube with a flangemount, as shown, that is fastened to the valve actuator 712 viafasteners 705.

The valve actuator 712 can comprise a piston 713 and an actuator device715, such as an arrangement with voice coils. The actuator device 715can be electrically coupled to a power source and a controller (notshown) to electrically control the actuator device 715 to axially movethe piston 713 along the axis of rotation 137, for instance. Therefore,the valve actuator 712 is configured to axially move the coupled movablevalve component 707 and the first valve body 709 between the open,partially open, and closed positions (further described below regardingFIGS. 18C and 18D).

The valve device 706 can further comprise a second valve body 717 havinga central opening 718 that slidable receives and supports the firstvalve body 709. The second valve body 717 comprises a first annularchannel 711 having a plurality of first openings 723 a formed throughthe second valve body 717 and disposed or positioned around the firstannular channel 711. The plurality of first openings 723 a are each influid communication with the second channel 288 b of the first vanedevice 164 (see FIG. 18C), and the second channel 288 b can be in fluidcommunication with an expansion gas chamber (e.g., such as expansionchamber 264 b of FIGS. 11A and 11B) via the conduit 290 b of the firstvane device 164, as discussed above regarding FIGS. 14A and 14B.

The second valve body 717 comprises a second annular channel 719 havinga plurality of second openings 723 b formed through the second valvebody 717 and disposed or positioned around the second annular channel719. The second valve body 717 can comprise interface portions 725 a-cadjacent and separating the respective annular channels 711 and 719, andthat are configured to engage and to interface with the inner surfacedefining the opening 277 of the first vane device 164. Each interfaceportion 725 a-c can further support one or more seals operable to sealoff gasses between the first and second openings 723 a and 723 b. A capmember 735 can be coupled to an end of the second valve body 717 to sealoff the inner chamber area of the valve assembly 706.

The plurality of second openings 723 b are each in fluid communicationwith the first channel 288 a of the first vane device 164 (see FIG.18C), which is in fluid communication with a compression chamber (e.g.,264 a) via the conduit 290 a, as discussed above.

The first valve body 709 can comprise a first annular stop portion 727and a second annular stop portion 729 formed on opposing sides of thestructure defining the annular passageway 731. The annular passageway731 can have curved surfaces that extend from respective stop portions727 and 729 toward a neck portion. The annular passageway 731 can beconfigured to permit fluid flow between the first and second openings723 a and 723 b (when in the open or partially open position) of thesecond valve body 717.

FIG. 18C illustrates the valve device 706 in the open position,specifically showing the movable valve component 707 and the first valvebody 709 as retracted by the piston 713, which exposes or uncovers thefirst and second openings 723 a and 723 b of the second valve body 717.Thus, the first and second openings 723 a and 723 b are in fluidcommunication with each other about the annular passageway 731 of thefirst valve body 709, which thereby places the conduits 290 a and 290 b(FIGS. 16A and 16B) in fluid communication, which thereby places thecompression and expansion chambers (e.g., 264 a and 264 b) in fluidcommunication. In this open position, the quasi-passive elastic actuatoris caused to enter the inelastic state, wherein pressures within thechambers of the quasi-passive elastic actuator are equalized, asdiscussed herein. Such open position can occur during free swing mode ofa robotic joint, for instance.

Conversely, FIG. 18D illustrates the valve device 706 in the closedposition, specifically showing the movable valve component 707 and thefirst valve body 709 extended by the piston 713 (upon actuation), whichposition functions to block or cover the first openings 723 a of thesecond valve body 717. In this position, the second openings 723 b arenot in fluid communication with the first openings 723 a of the secondvalve body 717, thereby restricting fluid flow between the conduits 290a and 290 b, which thereby restricts fluid flow between the compressionand expansion chambers (e.g., 264 a and 264 b, FIG. 11A), such that thequasi-passive elastic actuator is caused to enter the elastic state tostore or release energy (depending on the respective gait motion, forinstance), as discussed above. Although not shown, the valve device 706can be positioned in the partially open position to plac thequasi-passive actuator in the semi-elastic state.

Notably, the first and second openings 723 a and 723 b are formedradially around the perimeter of the second valve body 717. Thisconfiguration provides a radial balance of gas pressure about the valvebodies 709 and 717 because an equal amount of gas pressure is enteringthe first and second openings 723 a and 723 b around the entireperimeter of the second valve body 717. And, because the first valvebody 709 is formed symmetrical along the x plane and along the y plane(FIG. 18A), gas pressure is exerted and balanced radially around theentire perimeter annular passageway 731 (whether the valve is in theopen, partially open or closed position). This tends to result in equalradial gas pressure being exerted to the first valve body 709 and themovable valve component 707, which reduces friction when the movablevalve component 707 is actuated between the open and closed positions.Providing radial gas pressure balancing can reduce the amount ofgenerated heat at a given speed at which the movable valve component 707(and the first valve body 709) is actuated.

Furthermore, the valve assembly 704 can be axially gas pressurebalanced. That is, the movable valve component 707 can comprise acylindrically shaped tube body (see FIG. 18A) that has at least onefluid opening 737 in constant fluid communication with chambers oneither side of the movable valve component 707, whether in the open,partially open or closed positions (similar in function as the axiallybalanced principle discussed regarding FIGS. 17A-17E). That is, pressureis equalized axially as the movable valve component 707 is moved betweenthe open and closed positions, which prevents gas pressure from beingexerted against the movable valve component 707 in the axial directionsduring switching the quasi-passive elastic actuator between inelasticand elastic states. As with the radial gas pressure balancing discussedabove, this axial balancing tends to result in equal axial gas pressurebeing exerted about the valve assembly 706, which reduces friction whenthe movable valve component 707 is actuated between the open, partiallyopen, and closed positions, and which reduces heat at a given speed atwhich the movable valve component 707 is actuated.

Additional valve assemblies can be incorporated with the quasi-passiveelastic actuators discussed herein, such as the various valve assembliesdiscussed in U.S. patent application Ser. No. 15/810,119, filed Nov. 12,2017, which is incorporated by reference in its entirely herein.

FIG. 19 is a graph illustrating performance values for joint dampingtorque vs. various rotary conduit sizes for a quasi-passive elasticactuator corresponding to a knee joint in accordance with an example ofthe present disclosure. More specifically, in some examples the openingof conduits (e.g., 290 a and 290 b) of a particular first vane device(e.g., 164) can be selected to comprise a particular size to facilitatea damping of a quasi-passive elastic actuator, as exemplified above.That is, by selecting a diameter of the conduits to be in the range of5-6 mm, for instance, the gas pressure difference between the expansionand compression chambers will result in a joint damping torque of lessthan approximately 1 N-m, as illustrated, even at the maximum estimatedjoint speed. This graph pertains to a nominal charge pressure of 1,525psi in the compression and expansion chambers of the quasi-passiveelastic actuator (e.g., having 137 cc), and for a tunable actuator jointmodule having a torque of 7 N-m/deg. In this example, the outer radiusof the quasi-passive elastic actuator is 1.625 in., and the inner radius(defined by the compression and expansion chambers) is 0.78 in., and thecylinder length is 1.5 in. (as defined by the compression and expansionchambers). The first vane device and the second vane device have avolume occupation of 45 deg., and the gas in the compression andexpansion chambers is charged at a 90 deg. position of the first vanedevice relative to the second vane device.

Various slew rates are represented on the graph of FIG. 19 ascorresponding to the rotational movement (deg.) of the joint per second.As can be appreciated by the graph, depending on the slew rate, as theconduit diameter increases, the joint damping torque (N-m) decreases.Therefore, a conduit diameter of about 3 mm will provide a greater jointdamping torque than one that is 6 mm, for instance. This can beadvantageous when designing differing joints, such as a knee jointmodule as compared to a hip joint module, because inherently lower orhigher damping toques would be generated by the selection of the size ofthe conduit diameter.

Note that spring stiffness is a function of piston/vane and chambergeometries, as well as gas pressure charge. Thus, the magnitude ofstiffness for a given joint module is adjustable for mission-specificpayloads and terrain-specific gaits while the active valve controlsexactly when that stiffness is engaged for energy recovery during thesupport phase (elastic state) and when it is disengaged during the freeswinging state (inelastic state). For instance, the compression andexpansion chambers can be selected to comprise a particular volume alongwith the density of the gas, while the conduits through the first vanedevice can be selected to corresponding sizes that do not undulyrestrict gas flow when in the inelastic state. Also, the particularjoint location is determinative of the magnitude of the selectedstiffness value. For instance, the charge pressure for a knee joint andthe joint speed would both be significantly larger than required from ahip joint.

FIGS. 20A-20F illustrate various aspects of a tunable actuator jointmodule 800 in accordance with an example of the present disclosure. Thetunable actuator joint module 800 can be incorporated into a robotic orrobot limb, such as into the exoskeleton robot shown in FIG. 1 or 4A-4B,to provide, for example, an ankle joint defining a flexion/extensiondegree of freedom, as further discussed below. Alternatively, thetunable actuator joint module 800 can be incorporated into a robot, suchas a robot exoskeleton or humanoid robot as an actuator for any joint,such as a knee joint, a hip joint, a shoulder joint, an elbow joint, orothers.

Generally, the tunable actuator joint module 800 can comprise an outputmember 802 a and an input member 802 b that can each be rotatable aboutan axis of rotation 804 (or rotatable about different axes). The tunableactuator joint module 800 can comprise a primary actuator 806 (e.g., anelectric motor, electromagnetic motor, etc.) operable to apply a primarytorque to rotate the output member 802 a about the axis of rotation 804.The tunable actuator joint module 800 can further comprise aquasi-passive elastic actuator 808, such as a quasi-passive linearpneumatic actuator as shown, that operates in parallel with the primaryactuator 806 in a similar manner as discussed above with respect to thequasi-passive rotary pneumatic actuator. Indeed, the quasi-passiveelastic actuator 808 is operable to selectively store energy upon afirst rotation or movement of the input member 802 b, and operable toselectively release energy upon a second rotation of the input member802 b to apply an augmented torque to assist rotation of the outputmember 802 a, and to minimize power consumption of the primary actuator806, or to apply a braking force to restrict rotation of the joint,similarly as described above with respect to the quasi-passive elasticactuator 134. The quasi-passive elastic actuator 808 can furthercomprise an elastic component in the form of a linear pneumatic springtunable to a desired joint stiffness value, as detailed below.

The input member 802 b can be coupled to a support member of a roboticassembly (e.g., a support member as part of a limb), such as supportmember 105 c of FIG. 4A. Note that the input member 802 b is showngenerically as a pin, but it will be appreciated that the support member105 c, for instance, can be fastened to either side of the quasi-passiveelastic actuator 808 about the location of the illustrated pin. In oneexample, a trunnion mount can be incorporated to mount the quasi-passiveelastic actuator 808 to a support member of a robotic assembly. Theoutput member 802 a can be formed as part of an output device 810 thatrotates about the axis of rotation 804, as shown. Alternatively, theoutput member 802 a can be a separate component coupled to the outputdevice 810. The output member 802 a can be coupled to a support memberof a robotic assembly, such as support member 105 d of FIG. 4A. As such,the tunable actuator joint module 800 can define a joint of the lowerlimb of the robotic exoskeleton corresponding to an ankle joint of anoperator.

The output device 810 can comprise a cylindrical gear body 812 having acoupling portion 814 that protrudes or extends from the gear body 812.The coupling portion can comprise a slot 816, and with reference to FIG.20B, a pin 818 can extend laterally through the slot 816 and can becoupled to the coupling portion 814 for rotatably coupling thequasi-passive elastic actuator 808 to the output device 810, asdiscussed below. The output device 810 can further comprise a ring gear820 coupled to the cylindrical gear body 812, and the ring gear 820 canbe rotatably coupled to the primary actuator 806 by a transmission belt822, such that the primary actuator 806 drives the ring gear 820 via thetransmission belt 822 to actuate the tunable joint module 800. Note thatthe transmission belt 822 can be replaced with other types oftorque-transmitting devices, such as those discussed above regarding thediscussion of belt 224.

Similar to the primary actuators discussed above, the primary actuator806 of FIG. 20A can comprise a motor 801 and a transmission, such as aplanetary transmission 803, operatively coupled to the motor 801. Themotor 801 and planetary transmission 803 can have the same or similarstructure and functionality as described above regarding the primaryactuator of FIG. 9A. A transfer wheel (not show here) can be coupled toa rotor 805 of the motor 801. As with FIG. 9A, the motor 801 can be aframeless brushless electric motor having a stator 807 coupled to aframe or other support structure. The transfer wheel that can beincorporated in FIG. 20A can be similar to the transfer wheel 198 ofFIG. 9A, specifically, the transfer wheel can be coupled to the rotor805 about perimeter fasteners, and the sun gear of the planetarytransmission 803 can be coupled to a central opening of the transferwheel (e.g., FIG. 9A). Thus, upon actuation of the motor 801, the rotor805 rotates the transfer wheel, which rotates the sun gear of theplanetary transmission 803. Upon rotation of the sun gear, the planetgears rotate the carrier, which rotates an output pulley 807 coupled tothe carrier of the planetary transmission 803 (such structure andfunctionality is similarly described regarding FIGS. 8A-9B, and will notbe discussed in greater detail here). Upon rotation of the output pulley809, the transmission belt 822 rotates the output device 810, which canrotate the output member 802 a relative to the input member 802 b. Thus,the primary actuator 806 is configured to apply a primary torque torotate the output member 802 a. In some examples, as also discussedabove regarding belt 224 of FIG. 6A, various other torque-transmittingdevices can replace the particular configuration of the belt 822 of FIG.20A, such as one or more belts or linkages or gears or tendons (orcombinations of such), and such alternatives can be arranged to have anaxis of rotation that is offset from (e.g., oriented in a directionalong a plane that is perpendicular or orthogonal or some other angleother than parallel) to the axis of rotation of the primary actuator801). And, various transmissions can be arranged to provide differentgear reductions from input to output, including a relatively high gearreduction (e.g., 20:1, or more), or a relatively low gear reduction(e.g., 1:1), or any gear reduction between these, depending on theparticular application. In some examples, the torque-transmitting devicein the form of belt 822, or such various alternative torque-transmittingdevices, can allow the primary actuator 801 to be remotely located awayfrom the output (i.e., the primary actuator 801 is located a givendistance away from the output of the tunable actuator joint module, butoperably connected thereto via the torque-transmitting device), whereinthe remotely located primary actuator 801 can be actuated and its torquetransferred to the output of the tunable actuatable joint modulecorresponding to a joint of the robotic system. For instance, theprimary actuator 801 could be located at a lower back area of anexoskeleton (e.g., FIG. 4A), while such alternative torque-transmittingdevice(s) could transfer the primary toque from the lower back area toan output member located in the tunable actuator joint module of theankle joint for actuating the ankle joint.

The quasi-passive elastic actuator 808 can comprise a housing 824 (e.g.,cylinder) that can contain pressurized gas. The housing 824 is supportedon either end by a lower seal body 826 a and an upper seal body 826 bformed to seal gas within the housing 824 (see FIG. 20D). A movablepiston rod 828 extends through apertures of each of the seal bodies 826a and 826 b, and through the housing 824 (FIG. 20C). A piston cylinder830 is coupled to a section of the piston rod 828, and both are linearlymovable through and within the housing 824. As shown in FIGS. 20C and20D, the piston cylinder 830 defines, in part, and divides a compressionchamber 832 a and an expansion chamber 832 b within the housing 824. Theposition of the piston cylinder 830 can be different depending upon thedesired performance. In one aspect, the piston cylinder 830 can bepositioned such that the compression and expansion chambers 832 a and832 b comprise equal volumes. In another aspect, the piston cylinder 830can be positioned such that the compression and expansion chambers 832 aand 832 b comprise disparate or different volumes. The advantages ofdesigning the compression and expansion chambers 832 a and 832 b havingdisparate volumes are similar or the same as described above withreference to the disparate volumes as described with reference to FIG.11B. In another example, the piston rod 828 of the quasi-passive elasticactuator 808 can be coupled to an output member via a four-bar linkageconfiguration.

Seal assemblies can be disposed in each of the upper and lower sealbodies 826 a and 826 b that slidably receive the piston rod 828 whilesealing gas within the housing 824. A coupling device 834 can be coupledto a lower end of the piston rod 828, and can comprise an aperturethrough which the pin 818 (FIG. 20B) extends through to rotatably couplethe quasi-passive elastic actuator 808 to the output device 810.

In one example, the tunable actuator joint module 800 comprises acontrol system for selectively controlling application of the augmentedtorque of the quasi-passive elastic actuator 808, or the braking force.Specifically, the control system comprises a valve assembly 838controllably operable to switch the quasi-passive elastic actuator 808between an elastic state, a semi-elastic state, and an inelastic state(similar to the valve assemblies and quasi-passive elastic actuatorsdiscussed above). In this example, the valve assembly 838 comprises avalve device 840 actuatable to allow, partially allow, or restrict/blockfluid (e.g., air) flow between compression and expansion chambers 832 aand 832 b. Accordingly, FIG. 20D shows the valve device 840 in the openposition that permits the shunting of fluid flow between the compressionand expansion chambers 832 a and 832 b, and FIG. 20E shows the valvedevice 840 in the closed position, wherein fluid flow between thecompression and expansion chambers 832 a and 832 b is restricted. Thus,the valve device 840 defines or comprises a shunt circuit thatfacilitates fluid flow between the compression and expansion chambersthrough the valve assembly. Although not shown, the valve device 840 canbe positioned in the partially open position to place the quasi-passiveactuator 808 in the semi-elastic state

Specifically, the valve device 840 can comprise a movable valvecomponent 841, a piston 843, and an actuator 845 (e.g., a voice coil),similar to the valve device of FIG. 17C. The movable valve component 841can be coupled to the piston 843 via one or more fasteners (e.g.,fastener 847). The actuator 845 can be supported and housed by a capmember 849 coupled to the upper seal body 826 b to partially house thevalve assembly 838. Therefore, upon supplying an electrical field to theactuator 845, the piston 843 moves the movable valve component 841between the open position (FIG. 20D), the partially open position, andclosed position (FIG. 20E).

The valve assembly 838 can comprise a valve body 842 generallycylindrical and tubular in shape, and supported in a chamber of theupper seal body 826 b. The valve body 842 can be similar to the valvebody 659 of FIG. 17C, such that the valve body 842 comprises an annularpassageway 844 formed annularly around a middle perimeter section of thevalve body 842. The valve body 842 further comprises a plurality ofopenings 846 (one labeled) formed radially around the valve body 842proximate the annular passageway 844. Thus, the movable valve component841, being slidably interfaced to an inner surface of the valve body842, can be axially moved to at least partially uncover the plurality ofopenings 846 (FIG. 20D) in the open and partially open positions, andmoved to cover the plurality of openings 846 (FIG. 20E) in the closedposition.

In this manner, the quasi-passive elastic actuator 808 can comprise atube 848 coupled between the upper and lower seal bodies 826 a and 826 b(FIG. 20C). The tube 848 can comprise a first conduit 850 in fluidcommunication with a passageway 852 (FIG. 20F) formed through the lowerseal body 826 a. The passageway 852 extends through the lower seal body826 a, and is in fluid communication with the expansion chamber 832 b,as shown by the dashed arrows showing the gas flow path. The firstconduit 850 is further in fluid communication with a valve chamber 854defined by the movable valve component 841 and the valve body 842 (FIG.20D). The upper seal body 826 b comprises a second conduit 856 in fluidcommunication with the compression chamber 832 a, and in selective fluidcommunication with the annular passageway 844 of the valve body 842 (andconsequently in fluid communication with the internal chamber 854).Thus, when in the open position of FIG. 20D, or partially open position,a gas flow path exists between the compression and expansion chambers832 a and 832 b about the first conduit 850, the internal chamber 854,the plurality of openings 846, the annular passageway 844, and thesecond conduit 856, as shown by the dashed arrows on FIGS. 20D and 20F.Conversely, when in the closed position of FIG. 20E, such fluid path isclosed off by the movable valve component 841 upon actuation of themovable valve component 841 to cover the plurality of openings 846. Thistwo-way valve function therefore facilitates the selective engaging,semi-engaging and disengaging of the quasi-passive actuator for thepurposes described herein.

In one example, the housing 824 may not be gas pressure charged and isat ambient gas pressure, such that the stiffness value of the tunableactuator joint module 800, and particularly the quasi-passive elasticactuator, is near ambient gas pressure. In another example, the housing824 can be gas pressure charged and tuned to define a predetermined gaspressure (e.g., 500-3000+psi) to define a given joint stiffness value,similar to that described above regarding the rotary pneumaticactuators. This pre-charged gas pressure can be achieved duringmanufacture, or in the field by a user (e.g., via a gas pressure sourceand valve, not shown). And, such pre-charged gas pressure can bedynamically modified (increased or decreased) by adding or relieving gaspressure in the housing 824 via a valve, for instance. This is anotherexample of what is meant by the term “tunable” actuator joint module,because the example actuator joint module 800 can be tuned to have aparticular joint stiffness value by selecting the amount of gas pressurecharged in (or removed from) the compression and expansion chambers.

The control system, including the valve assembly 838, can furthercomprise a computer system (not shown) having a controller electricallyor communicatively coupled to the valve assembly 838 (i.e., to theactuator 845) to apply an electrical field to control operation of theactuator 845 and the valve assembly, thereby switching the valve devicebetween the open, partially open and closed positions. The computersystem can be coupled to a power source, such as to a battery onboardthe robotic device (e.g., in a backpack) or to another power sourceassociated with the robot or robotic device.

In operation, upon a first rotation of the input member 802 b relativeto the output member 802 a (e.g., such as during a first segment of awalking or running gait cycle), and when the valve device 838 is in theclosed position, the piston rod 828 and the piston cylinder 830 moveupwardly relative to the housing 824, which functions to store gaspressure energy about the compression chamber 832 a. Upon a secondrotation of the input member 802 b relative to the output member 802 a(e.g., such as during a second segment of the gait cycle), this storedenergy can be released when gas pressure exerted against the pistoncylinder 830 is allowed to expand, which causes an axial biasing forceto the piston rod 828, which exerts an augmented torque to the outputdevice 802 a to rotate the output member 802 a of the output device 810in parallel with the primary torque being applied by the primaryactuator 806. This action can also be used to generate and apply abraking force to restrict rotation of the input member 802 b relative tothe output member 802 a. Upon a third rotation of the input member 802 brelative to the output member 802 a (e.g., during a swing phase of thegait cycle), the valve device 838 can be actuated to the open position,which equalizes pressure between the compression and expansion chambers832 a and 832 b, and which facilitates the shunting of fluid betweenthese two chambers, thus placing the quasi-passive actuator in theaforementioned free swing or inelastic mode. In this mode, negligibleresistance exists about the tunable actuator joint module 800 upon suchthird rotation of the input and output members 802 a and 802 b.

Therefore, in a practical example (and similar to the above discussionregarding the tunable actuator joint module 109 a), where the tunableactuator joint module 800 is incorporated into an ankle joint of arobotic assembly (e.g., exoskeleton joint 101 of FIG. 4A) to provide aflexion/extension degree of freedom, upon a first gait movement (e.g.,shortly after heel strike) the valve device 838 is controlled to be inthe closed position, thereby facilitating storage of energy about thequasi-passive elastic actuator 808, as discussed above. And, upon asecond gait movement (e.g., after heel strike and before toe-off) thevalve device 838 is maintained in the closed position to facilitate therelease of stored energy to apply the augmented torque to the primarytorque to actuate the ankle joint, as discussed above. As isspecifically discussed above, upon such second gait movement, theprimary actuator 806 can be actuated to apply a primary torque, alongwith the augmented torque applied by the quasi-passive elastic actuator808, to rotate the output member 802 a, as coupled to a support memberof a robotic assembly. Finally, upon a third gait movement (e.g., justbefore toe-off) the valve device 838 is actuated to the open position,as discussed above, to facilitate free swing of the ankle joint. Variousmovements can also be braked by operating the quasi-passive elasticactuator to apply a braking force.

In one specific example, the housing 824 can comprise a 155 cc volume,with the compression volume being 56 cc, and the expansion volume being99 cc (the compression and expansion chamber volumes being disparate asdefined by the positioning of the piston). The housing 824 can becharged to 1003 psi, with a 1577 peak psi at 20 degrees compression,which produces a 526 N-m torque. The piston rod 828 diameter can be0.3125 inches and the piston cylinder 830 1.75 inches. This can provideapproximately 25 N-m/degree joint stiffness value for a knee or anklejoint, for instance. This example is not intended to be limiting in anyway as will be apparent to those skilled in the art.

Note that the quasi-passive elastic actuators discussed herein (i.e.,rotary and linear) can be charged with a two-phase fluid. For instance,a quasi-passive elastic actuator can be pressure charged with afluorocarbon or fluorocarbon refrigerant (e.g., Freon), which caninitially be in a gaseous state when the quasi-passive elastic actuatoris pre-charged or in a nominal position, wherein upon pressure orcompression of the gas inside the compression chamber (due to rotationof the joint), the gaseous fluid can transition to a liquid state. Thisprovides the tunable actuator joint module with the advantageousproperties of a liquid under compression, as compared to a gaseousfluid, which can enhance the stability of the system.

In one example, the combined output torque (i.e., the primary torquecombined with the augmented torque) provided by the tunable actuatorjoint module 800 can be selected to be a predetermined output torque. Inone aspect, this can be based on the selected position of the couplingbetween the piston rod 828 and the output member 802 a. For instance, asshown in FIG. 20A the piston rod 828 can be coupled to the output device810 at an off-center position relative to the axis of rotation 804, andat a predefined distance from the axis of rotation 804, and alsooptionally at a predefined angle.

In an alternative example, a single-rod linear pneumatic spring can beincorporated. For instance, piston rod 828 would not extend through atop of the housing 824, and instead it would terminate at the pistoncylinder 830. In this manner, such piston cylinder could be originallypositioned in the housing at a middle area such that the compression andexpansion chambers have equal volume, or positioned away from the middlearea of the housing to provide disparate volumes of the compression andexpansion chambers.

As indicated above, in examples where a particular tunable actuatorjoint module discussed herein is incorporated as a joint in an upperbody exoskeleton, the quasi-passive elastic actuators can provide agravity compensation function, such as when arms are raised to supportbody armor and/or weapons. That is, when the arm is raised whilesupporting a load, the quasi-passive elastic actuator can be operable toapply an augmented torque to resist the forces of gravity acting on theload and to assist in lifting the load. In examples where a particulartunable actuator joint module as discussed herein is incorporated as ajoint of a lower body exoskeleton, the tunable actuator joint module canbe designed for a maximum torque of 250 N-m, while the quasi-passiveelastic actuator can be designed for a 7 N-m/degree spring stiffnessvalue for a knee joint, and a 3 N-m/degree for a hip joint, forinstance. Because cyclic gaits such as walking typically do not exceed20 degrees, the total torque provided by a lower body tunable actuatorjoint module can be approximately 140 N-m in normal operation.

FIG. 21 illustrates a quasi-passive elastic actuator 900 that can becoupled remotely away from an ankle joint rotation 902, for instance.The quasi-passive elastic actuator 900 can have the same or similarfeatures as that of the quasi-passive elastic actuator 808 discussedabove, such as having a control system, including the valve assembly838. In this example, the quasi-passive elastic actuator 900 can beremotely coupled anywhere along a support member of a robotic system(such as an exoskeleton, humanoid or other robotic system ascontemplated herein). For example, the quasi-passive elastic actuator900 can be remotely coupled to a support member 904 corresponding to afemur of an operator wearing an exoskeleton, therefore being positioneddistally away from the axis of rotation of the output member. As in theexample shown, a Bowden cable 906 (or other similar semi-flexible forcetransmitting device, or other transmission device) could be coupledbetween a piston cylinder 908 of the quasi-passive elastic actuator 900and an output member 910 associated with the ankle joint 902 foractuating the ankle joint 902 to move an ankle support member 912 onwhich the operator's foot is supported. In one aspect, being “remotelylocated” can mean that at least one joint (e.g., the knee joint 914) isdisposed or positioned between the quasi-passive elastic actuator 900(the device storing energy and releasing energy to apply a torque) andthe joint associated with the quasi-passive elastic actuator 900 that isto be actuated, which is the ankle joint 902 in this example. In someexamples, a primary actuator (e.g., motor) can be coupled adjacent thequasi-passive elastic actuator 900 (e.g., coupled to support member 904)and to the Bowden cable 906 to apply a primary torque via the Bowdencable 906 to actuate the joint, in this case the ankle joint 902.Alternatively, the primary actuator can be coupled locally, such as ator near the joint (e.g., the ankle joint 902) to apply a primary torque(whether in parallel or series) along with the augmented torque appliedby the quasi-passive elastic actuator 900.

In operation, using the example arrangement shown, upon a first rotationof the ankle joint 902 (i.e., just after heel strike during stancecompression) the quasi-passive elastic actuator 900 is operable to storeenergy when operated in an elastic state (because the piston cylinder908 is moved upwardly though a housing to store energy in a compressionchamber, similarly as discussed regarding quasi-passive elastic actuator808). And, upon a second rotation of the ankle joint 902 (i.e., afterheel strike and up to toe-off during stance extension), thequasi-passive elastic actuator 900 is operable to release the storedenergy, when operated in the elastic state, to apply a torque (e.g.,augmented with a primary torque in one example) to actuate the anklejoint 902 via the Bowden cable 906. Optionally, during a third rotation(i.e., from toe-off to heel strike), the quasi-passive elastic actuator900 can be switched (via a valve) to operate in an inelastic state, suchthat no energy is being stored or released via the quasi-passive elasticactuator 900, thereby allowing the ankle joint 902 to be in a free-swingmode.

The quasi-passive elastic actuator 900 is shown as comprising an elasticcomponent in the form of a linear pneumatic spring, but alternativelycan be a rotary pneumatic spring (such as exemplified herein), or even amechanical spring, such as a coil spring, polymer spring, torsionalspring, or other elastic component.

Remotely locating the quasi-passive elastic actuator, by itself or withone or more additional components of the tunable actuator joint module,can remotely place the mass of the quasi-passive elastic actuator 900(and perhaps a primary actuator) closer to the center of gravity of therobotic system (e.g., closer to the center of gravity of an exoskeletonand an operator of the exoskeleton), which can reduce the moment ofinertia during joint rotation (e.g., gait movements), which therebyfurther reduces or minimizes the power dissipation required to actuatethe joint. Therefore, the quasi-passive elastic actuator 900 (andoptionally a primary actuator) can be sized smaller than normallyrequired when located locally near the joint.

The tunable actuator joint modules discussed herein can be controlled bya controller of a computer system, whether located on-board of the robotor robotic device or remotely located such that the robot or roboticdevice is in communication with the computer system using knowncommunication techniques and methods. In addition, the controller can beused to control each of the tunable joint actuator modules in a robot orrobotic device, and to operate these in a coordinated manner (e.g.,within a robotic exoskeleton, operate a tunable actuator knee jointmodule with that of a tunable actuator hip module or tunable actuatorankle module, such that each of these functions with the other toprovide human kinematic equivalent motions, such as during walking,running, squatting, or other movements). For example, assume a lowerbody exoskeleton is worn by a human operator during a running gaitcycle, and assume left/right ankle joints each include the tunableactuator joint module 800, and left/right knee and hip joints eachinclude a tunable actuator joint module (109 a, 130, or 500), discussedin detail above. The computer system can receive position and force datafrom position or force sensors, or both, associated with each of saidtunable actuator joint modules. The position and force data can beprocessed to generate information that determines the particularrespective positions of each of said tunable actuator joint modules, orthe forces acting thereon, and one or more gait recognition algorithmscan process such information to determine which (if any) of said tunableactuator joint modules are to switch between elastic, semi-elastic andinelastic states. Accordingly, the computer system can generate andtransmit command signals to respective tunable actuator joint module(s)to actuate the respective valve assemblies to the appropriate open orclosed positions, and/or to actuate respective electric motors to applya primary torque. Such processing can be performed in milliseconds andon a continuous basis during the gait cycle, for instance, for everytunable actuator joint module. The same holds true for task-specificmovements, such as walking, jumping, squatting, climbing or othermovements.

It is further noted that rotation of the joints (i.e., relative rotationbetween the input and output members) defined by the various tunableactuator joint modules discussed herein can be in any direction (e.g.,the same direction, different directions) during the storing andreleasing of the energy, during the generation and application of abraking force, as well as the opening of the valve assemblies and theshunt circuits to facilitate free swing of the joints. In other words,the valve assemblies can be operated to engage to store energy, torelease energy, or to disengage to facilitate free swing of the jointupon rotation of an associated joint in the same direction or in variousdifferent directions. This is the case for all of the examples set forthin the present disclosure.

It is to be understood that the embodiments of the invention disclosedare not limited to the particular structures, process steps, ormaterials disclosed herein, but are extended to equivalents thereof aswould be recognized by those ordinarily skilled in the relevant arts. Itshould also be understood that terminology employed herein is used forthe purpose of describing particular embodiments only and is notintended to be limiting.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, appearancesof the phrases “in one embodiment” or “in an embodiment” in variousplaces throughout this specification are not necessarily all referringto the same embodiment.

Although the disclosure may not expressly disclose that some embodimentsor features described herein may be combined with other embodiments orfeatures described herein, this disclosure should be read to describeany such combinations that would be practicable by one of ordinary skillin the art. The user of “or” in this disclosure should be understood tomean non-exclusive or, i.e., “and/or,” unless otherwise indicatedherein.

As used herein, a plurality of items, structural elements, compositionalelements, and/or materials may be presented in a common list forconvenience. However, these lists should be construed as though eachmember of the list is individually identified as a separate and uniquemember. Thus, no individual member of such list should be construed as ade facto equivalent of any other member of the same list solely based ontheir presentation in a common group without indications to thecontrary. In addition, various embodiments and example of the presentinvention may be referred to herein along with alternatives for thevarious components thereof. It is understood that such embodiments,examples, and alternatives are not to be construed as de factoequivalents of one another, but are to be considered as separate andautonomous representations of the present invention.

Furthermore, the described features, structures, or characteristics maybe combined in any suitable manner in one or more embodiments. In thedescription, numerous specific details are provided, such as examples oflengths, widths, shapes, etc., to provide a thorough understanding ofembodiments of the invention. One skilled in the relevant art willrecognize, however, that the invention can be practiced without one ormore of the specific details, or with other methods, components,materials, etc. In other instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of the invention.

While the foregoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

What is claimed is:
 1. A method for operating a robotic systemcomprising at least one tunable joint module, the method comprising:causing a first rotation of a tunable actuator joint module of a roboticassembly; engaging a quasi-passive elastic actuator of the tunable jointmodule during the first rotation to store energy; and actuating aprimary actuator to apply a primary torque and cause a second rotationof the tunable actuator joint module in a different direction from thefirst rotation, the quasi-passive actuator releasing the stored energyand applying an augmented torque to the primary torque during the secondrotation, thereby reducing the power needed by the primary actuator toapply the primary torque to cause the second rotation.
 2. The method ofclaim 1, further comprising disengaging the quasi-passive elasticactuator, such that it enters an inelastic state and a free-swing mode.3. The method of claim 2, wherein disengaging the quasi-passive elasticactuator occurs during a third rotation of the tunable actuator jointmodule.
 4. The method of claim 1, wherein engaging the quasi-passiveelastic actuator comprises causing the quasi-passive elastic actuator toenter an elastic state.
 5. The method of claim 4, further comprising, inthe elastic state, compressing a gas within a compression chamber of ahousing of the quasi-passive actuator to store the energy, and expandingthe gas about an expansion chamber of the housing to release the energy.6. The method of claim 1, further comprising, prior to the firstrotation, providing a pressure differential between the compressionchamber and the expansion chamber.
 7. The method of claim 1, furthercomprising selectively operating a valve assembly to permit or restrictthe flow of the gas, and thereby engage, partially engage, or disengagethe quasi-passive elastic actuator.
 8. The method of claim 1, furthercomprising opening a shunt circuit to facilitate the flow of gas betweenthe compression and expansion chambers of the quasi-passive elasticactuator and the valve assembly with the quasi-passive elastic actuatorin the inelastic state, the opening of the shunt circuit facilitatingfree-swing of the tunable joint module.
 9. The method of claim 1,further comprising providing the quasi-passive elastic actuator with adesired gas pressure to define a predetermined joint stiffness value.10. The method of claim 9, further comprising modifying the gas pressureto modify the joint stiffness value.
 11. The method of claim 1, furthercomprising coordinating operation of a plurality of tunable jointmodules of the robotic system, one of the plurality of tunable jointmodules defining a hip joint of the robotic system, one of the tunablejoint modules defining a knee joint of the robotic system, one of theplurality of tunable joint modules defining an ankle joint of therobotic system, or a combination of these.
 12. The method of claim 1,wherein causing a first rotation of a tunable actuator joint modulecomprises actuating a primary actuator of the tunable joint module toapply a primary torque with the quasi-passive elastic actuator in theelastic state.
 13. A method of making a tunable actuator joint modulefor use within a robotic system, the method comprising: configuring aprimary actuator to apply a torque about an axis of rotation of a jointof a robotic system; and configuring a quasi-passive elastic actuator tooperate with the primary actuator, the quasi-passive elastic actuatorcomprising an elastic component dynamically tunable to a joint stiffnessvalue, the quasi-passive elastic actuator operable to selectively storeenergy upon a first rotation of the joint, and operable to selectivelyrelease energy upon a second rotation of the joint to apply an augmentedtorque to the primary torque to assist rotation of the joint during thesecond rotation.
 14. The method of claim 13, further comprisingequipping the quasi-passive elastic actuator with a valve assemblyoperable to switch the quasi-passive elastic actuator between theelastic state and the inelastic state.
 15. The method of claim 13,further comprising forming a shunt circuit in the quasi-passive elasticactuator that is engageable to facilitate the flow of gas between thevalve assembly and a housing of the elastic component of thequasi-passive actuator, and that is disengageable to restrict the gasfrom flowing through the valve assembly.
 16. The method of claim 15,further comprising configuring the housing with a compression chamberand an expansion chamber.
 17. The method of claim 16, further comprisingconfiguring the compression chamber and the expansion chamber tocomprise different volumes.
 18. The method of claim 13, wherein couplinga quasi-passive elastic actuator to the primary actuator comprisescoupling one of a quasi-passive rotary pneumatic actuator or aquasi-passive linear pneumatic actuator to the primary actuator.